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The Soar User`s Manual Version 8.6.3

1. 024 11 21 7 Applying the operator gt lt lt o s s ssai OA eae HO 11 2 1 8 Making inferences about the state 0 12 OO Problem Opak lt esce ee es a pea ee BE ee eS 12 Working memory The Current Situation ooa e a a aa 14 Production Memory Long term Knowledge 16 2 3 1 The structure of a production s ss ss 46 4 erasi ii 16 2 3 2 Architectural roles of productions 18 2 3 3 Production Actions and Persistence 18 Preference memory Selection Knowledge ooa aa aaa 19 2 4 1 Preference semantics ooo 0 e eee eee ene 20 Soar s Execution Cycle Without Substates 22 Impasses and Substates 2 1 a a a 22 2 0 1 Impass Types e co e ee ewe Se eee Oe hee KE Geci 23 20 2 Creating New States oo a coso ra roaba s oha 24 SO E a 25 Pie Pe ye e a ey 8 e e hE e up e e 27 2 6 4 Removal of Substates Impasse Resolution 28 2 6 5 Soar s Cycle With Substates ao oaoa 31 PRN ee ee E E E E me E E 31 Input and Output lee ee eee eed eee de a oe ee 32 ii CONTENTS 3 The Syntax of Soar Programs 33 ool Working Memory ss se ecra rarse s bd Goeto ee SES oea s 33 odl yO s s ie eR ee EEE eM eee aes Ss 34 al IOC ssd 624 24Gb owed Ea a aD SEES 34 la Leaps sonr eoh ee a be ote BB EOS Aw ee ee Ses 30 3 1 4 Acceptable preferences in working memory 36 3 1 5 Working Memory asa Graph 44 37 3 2 Preferenc
2. Denil BOuUrCe ck he we ae HR DOE we a emg 56 Soar lO Commands s s s 4a doe d ob a ee ed ia 0 6 1 add wme 20 000 5 6 2 rvemove wme 5 7 Miscellaneous 2 44 4 4444 244 be woe ew Blade Aliase ts oe Sed Gh a ce ED Se Ge 5 7 2 dit production 5 7 3 input period ik bh kw Re RR RS Did Send oa a wk heath eh tp A Sod CEES 5 7 5 SOAYNEWS 66 6 eee eee ees DLG time eke ae ae OP ee Shee Ee Dist unalias o esre ee we we eos 5 7 8 version 0 0084 Appendices A The Blocks World Program B Grammars for production syntax B 1 Grammar of Soar productions lt 5 44 4 B 1 1 Grammar for Condition Side B 1 2 Grammar for Action Side C The Calculation of O Support D The Resolution of Operator Preferences E A Goal Dependency Set Primer Index Summary of Soar Aliases Variables and Functions CONTENTS 157 157 163 a pre we aA 163 a miaa 163 dre a oe a og a 164 165 167 171 179 185 List of Figures 2 2 2 2 3 2 4 2 9 20 A 2 5 29 2 10 3 1 3 2 3 3 3 4 Da E 1 E2 E 3 E 4 Soar is continually trying to select and apply operators The initial state and goal of the blocks world task An abstract illustration of the initial state of the blocks world as working memory objects At this stage of problem solving no operators have been proposed
3. lt s gt ontop lt o 1 gt lt o 1l gt bottom object lt b 1 gt lt b 1 gt name table gt lt s gt nothing ontop a or table true Notes on attribute path notation e Attributes specified in attribute path notation may not start with a digit For example if you type foo 3 bar Soar thinks the 3 is a floating point number Attributes that don t appear in path notation can begin with a number e Attribute path notation may be used to any depth e Attribute path notation may be combined with structured values described in Section 3 3 5 12 3 3 PRODUCTION MEMORY 55 3 3 5 12 Structured value notation Another convenience that eliminates the use of intermediate variables is structured value notation Syntactically the attributes and values of a condition may be written where a variable would normally be written The attribute value structure is delimited by parentheses Using structured value notation the production in Figure 3 2 on page 39 may also be written as sp blocks world propose move block state lt s gt problem space blocks thing lt thing1 gt lt gt lt thing1l gt lt thing2 gt ontop top block lt thing1 gt pottom block lt gt lt thing2 gt lt thing1 gt type block clear yes lt thing2 gt clear yes gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt destination lt thi
4. Soar determines I support or O support for the justification just as it would for any other production as described in Section 2 3 3 If the justification is an operator application the result will receive O support Otherwise the result gets I support from the justification If such a result loses I support from the justification it will be retracted if there is no other support Justification are not added to production memory but are otherwise treated as an instantiated productions that have already fired Justifications include any negated conditions that were in the original productions that participated in producing the results and that test for the absence of superstate working memory elements Negated conditions that test for the absence of working memory elements that are local to the substate are not included which can lead to overgeneralization in the justification see Section 4 6 on page 80 for details 2 6 4 Removal of Substates Impasse Resolution Problem solving in substates is an important part of what Soar does and an operator impasse does not necessarily indicate a problem in the Soar program They are a way to decompose a complex problem into smaller parts and they provide a context for a program to deliberate about which operator to select Operator impasses are necessary for example for Soar to do any learning about problem solving as will be discussed in Chapter 4 This section describes how impasses may be reso
5. sp operator augmentation application state lt s gt task test support operator lt o gt gt lt o gt new augmentation lt s gt new augmentation In o support mode 3 both RHS actions receive o support in o support mode 4 both receive i support In either case Soar will print a warning on firing this production because this is considered bad coding style Appendix D The Resolution of Operator Preferences During the decision phase operator preferences are evaluated in a sequence of eight steps in an effort to select a single operator Each step handles a specific type of preference as illustrated in Figure D 1 The figure should be read starting at the top where all the operator preferences are collected and passed into the procedure At each step the procedure either exits through a arrow to the right or passes to the next step through an arrow to the left Input to the procedure are the set of current operator preferences and the output consists of 1 a subset of the candidate operators either the empty set a set consisting of a single winning candidate or a larger set of candidates that may be conflicting tied or indifferent 2 an impasse type possibly NONE_IMPASSE_TYPE The procedure has several potential exit points Some occur when the procedure has detected a particular type of impasse The others occur when the number of candidates has been reduced to one necessarily the winn
6. 1 The block that is being moved is no longer where it was it is no longer on top of the same thing 2 The block that is being moved is now in a new location it is on top of a new thing 3 The place that the block used to be is now clear 4 The place that the block is moving to is no longer clear unless it is the table which is always considered clear 1 The blocks world task could also be implemented using an external simulator In this case the Soar program does not update all the on top and clear relations the updated state description comes from the simulator 2 1 8 Making inferences about the state Making monotonic inferences about the state is the other role that Soar long term knowledge may fulfill Such elaboration knowledge can simplify the encoding of op erators because entailments of a set of core features of a state do not have to be explicitly included in application of the operator In Soar these inferences will be automatically retracted when the situation changes such that the inference no longer holds For instance our example blocks world task uses an elaboration to keep track of whether or not a block is clear The elaboration tests for the absence of a block that is on top of a particular block if there is no such on top the block is clear When an operator application creates a new on top the corresponding elaboration retracts and the bloc
7. 22 CHAPTER 2 THE SOAR ARCHITECTURE 2 5 Soar s Execution Cycle Without Substates The execution of a Soar program proceeds through a number of cycles Each cycle has five phases 1 Input New sensory data comes into working memory 2 Proposal Productions fire and retract to interpret new data state elabo ration propose operators for the current situation operator proposal and compare proposed operators operator comparison All of the actions of these productions are I supported All matched productions fire in parallel and all retractions occur in parallel and matching and firing continues until there are no more additional complete matches or retractions of productions quiescence 3 Decision A new operator is selected or an impasse is detected and a new state is created 4 Application Productions fire to apply the operator operator application The actions of these productions will be O supported Because of changes from operator application productions other productions with I supported actions may also match or retract Just as during proposal productions fire and retract in parallel until quiescence 5 Output Output commands are sent to the external environment The cycles continue until the halt action is issued from the Soar program as the action of a production or until Soar is interrupted by the user During the processing of these phases it is possible that the preferences that resulted in
8. There can be only one type of impasse at a given level of subgoaling at a time Given the semantics of the preferences it is possible to have a tie or conflict impasse and a constraint failure impasse at the same time In these cases Soar detects only the constraint failure impasse The impasse is detected during the selection of the operator but happens because one of the other four problem solving functions was incomplete 2 6 2 Creating New States Soar handles these inconsistencies by creating a new state in which the goal of the problem solving is to resolve the impasse Thus in the substate operators will be selected and applied in an attempt either to discover which of the tied operators should be selected or to apply the selected operator piece by piece The substate is often called a subgoal because it exists to resolve the impasse but is sometimes called a substate because the representation of the subgoal in Soar is as a state The initial state in the subgoal contains a complete description of the cause of the impasse such as the operators that could not be decided among or that there were no operators proposed and the state that the impasse arose in From the perspective of the new state the latter is called the superstate Thus the superstate is part of the substructure of each state represented by the Soar architecture using the superstate attribute The initial state created in the Oth decision cycle contains a supe
9. contains 043 and 053 contains 087 respectively the contains attribute is a multi valued attribute Likewise object 053 is linked to object 043 through 043 38 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS inside 053 and linked to object 087 through 087 inside 053 Object X44 is linked to object 043 through 043 X44 200 Links are transitive so that X44 is linked to 053 because 043 is linked to 053 and X44 is linked to 043 However since links are not symmetric 053 is not linked to X44 3 2 Preference Memory Preferences are created by production firings and express the relative or absolute mer its for selecting an operator for a state When preferences express an absolute rating they are identifier attribute value preference quadruples when preferences express relative ratings they are identifier attribute value preference value quintuples For example S1 operator 03 is a preference that asserts that operator O3 is an acceptable operator for state S1 while S1 operator 03 gt 04 is a preference that asserts that operator O3 is a better choice for the operator of state S1 than operator O4 The semantics of preferences and how they are processed were described in Section 2 4 which also described each of the eleven different types of preferences Multiple production instantiations may create identical preferences Unlike working memory preference memory is not a set Duplicate preferences are
10. state not goal At the kernel level states are still called goals and goal is often still used to refer to states As a result a confusion in terminology results with Goal 171 172 APPENDIX E A GOAL DEPENDENCY SET PRIMER preference This preference makes the resulting WME persistent it will remain in memory until explicitly removed or until its local state is removed regardless of whether it continues to be justified Persistent WMEs are pervasive in Soar because operators are the main unit of prob lem solving Persistence is necessary for taking any non monotonic step in a problem space However persistent WMEs also are dependent on WMEs in the superstate context The problem in Soar 7 especially when trying to create large scale systems like TacAir Soar is that the knowledge developer must always think about which dependencies can be ignored and which need to result in a reconsideration of the persistent WME For example imagine an exploration robot that makes a persistent decision to travel to some distant destination based in part on its power reserves Now suppose that the agent notices that its power reserves have failed If this change is not communicated to the state where the travel decision was made the agent will continue to act as if its full power reserves were still available Of course for this specific example the knowledge designer can encode some knowl edge to react to this i
11. Load and evaluate the contents of a file The source command is used for nearly every Soar program The directory func tions are important to understand so that users can navigate directories folders to load save the files of interest Soar applications that include a graphical interface or other simulation environment will often require the use of echo 5 5 1 cd Change directory Synopsis cd directory Options directory The directory to change to can be relative or full path Description Change the current working directory If run with no arguments returns to the directory that the command line interface was started in often referred to as the home directory 138 CHAPTER 5 THE SOAR USER INTERFACE Examples To move to the relative directory named home soar agents cd home soar agents Default Aliases Alias Maps to chdir cd See Also dirs ls pushd popd source 5 5 2 clog Record all user interface input and output to a file Synopsis clog Ae filename clog a string clog cdoq Options filename Open filename and begin logging c close Stop logging close the file o off d disable a add string Add the given string to the open log file q query Returns open if logging is active or closed if logging is not active A append e Opens existing log file named filename existing and logging is ad
12. OK but try to avoid Be careful of where the level is on the command line for example if you want level 2 and preferences watch r 1 2 Incorrect r flag ignored level 2 parsed after it and overrid watch r 2 Syntax error 0 or remove expected as optional argument to r watch r 1 2 Incorrect r flag ignored level 2 parsed after it and overri watch 2 r OK but try to avoid watch 1 2 r 0K To turn on printing of decisions phases and productions do any one of the following not all possibilities listed watch level 3 watch 1 3 watch decisions phases productions watch d p P Individual options can be changed as well To turn on printing of decisions and wmes but not phases and productions do any one of the following not all possibilities listed 118 CHAPTER 5 THE SOAR USER INTERFACE watch level 1 wmes watch 1 1 w watch decisions wmes watch d wmes watch w decisions watch w d To turn on printing of decisions productions and wmes and turns phases off do any one of the following not all possibilities listed watch level 4 phases remove watch l 4 p remove watch 1 4 p 0 watch d P w p remove To watch the firing and retraction of decisions and only user productions do any one of the following not all possibilities listed watch 1 1 u watch d u To watch decisions phases and all productions except user productions and ju
13. disable off Turn verbosity off e enable on Turn verbosity on Description Invoke with no arguments to query current setting 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 113 5 3 6 warnings Synopsis warnings eld Options e enable on Default Print all warning messages from the kernel d disable off Disable all except most critical warning messages Description Enables and disables the printing of warning messages If an argument is specified then the warnings are set to that state If no argument is given then the current warnings status is printed At startup warnings are initially enabled If warnings are disabled using this command then some warnings may still be printed since some are considered too important to ignore The warnings that are printed apply to the syntax of the productions to notify the user when they are not in the correct syntax When a lefthand side error is discovered such as conditions that are not linked to a common state or impasse object the production is generally loaded into production memory anyway although this production may never match or may seriously slow down the matching process In this case a warning would be printed only if warnings were on Righthand side errors such as preferences that are not linked to the state usually result in the production not being loaded and a warning regardless of the warnings setti
14. help excise To see what commands help is available for help Default Aliases Alias Maps to help h help man help 5 1 3 init soar Empties working memory and resets run time statistics 5 1 BASIC COMMANDS FOR RUNNING SOAR 87 Synopsis init soar Options No options Description The init soar command initializes Soar It removes all elements from working mem ory wiping out the goal stack and resets all runtime statistics The firing counts for all productions are reset to zero The init soar command allows a Soar program that has been halted to be reset and start its execution from the beginning init soar does not remove any productions from production memory to do this use the excise command Note however that all justifications will be removed because they will no longer be supported Default Aliases Alias Maps to init init soar is init soar See Also excise 5 1 4 quit Close log file terminate Soar and return user to the operating system Synopsis quit Options No options 88 Description CHAPTER 5 THE SOAR USER INTERFACE This command stops the run quits the log and closes Soar Default Aliases Alias Maps to exit quit 5 1 5 run Begin Soar s execution cycle Synopsis run f count run dlelolp s un f count run dlelolp un count i lt elpldlo gt
15. 04 has moving block B2 B1 B2 is clear B3 is clear 04 has destination B1 B1 is a block i T1 O5 is named move block B1 is named A Tis atabl 05 O5 has moving block B3 B1 is clear T1 is named table O5 has des natitn B1 S1 T1 is clear O6 is named nove block S1 is a state 06 O6 has moving bldck B1 S1 has a problem spa c blocks O6 has dwstina 1 has a thing B1 1 has a thing B2 S1 has a thing B3 S1 has a thing T1 S1 has an ontop O1 S1 has an ontop O2 S1 has an ontop O3 S1 has operator O7 S1 has sjx proposed opera 07 O7 is named move block O7 has moving block B3 07 07 has destination B2 01 O1 hds a top block B41 O1 has a bottom block T1 O2 has a top block B2 02 O2 has a boitom block T1 03 O3 has a top block B3 O3 has a bottom block T1 An Abstract View of Working Memory Figure 2 4 An abstract illustration of working memory in the blocks world after the first operator has been selected JEE nitial State move C on top of A move A on ee ai be 0 of B Figure 2 5 The six operators proposed for the initial state of the blocks world each move one block to a new location 2 1 AN OVERVIEW OF SOAR 11 or absolute merits of the candidate operators For example a preference may say that operator A is a better choice
16. 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 109 Warnings Firing counts are reset to zero after an init soar NB This command is slow because the sorting takes time O n log n Default Aliases Alias Maps to fc firing counts See Also init soar 5 3 3 pwatch Trace firings and retractions of specific productions Synopsis pwatch dle production name Options d disable off Turn production watching off for the specified produc tion If no production is specified turn production watching off for all productions e enable on Turn production watching on for the specified produc tion The use of this flag is optional so this is pwatch s default behavior If no production is specified all pro ductions currently being watched are listed production name The name of the production to watch Description The pwatch command enables and disables the tracing of the firings and retractions of individual productions This is a companion command to watch which cannot specify individual productions by name With no arguments pwatch lists the productions currently being traced With one production name argument pwatch enables tracing the production enable can be explicitly stated but it is the default action 110 CHAPTER 5 THE SOAR USER INTERFACE If disable is specified followed by a production name tracing is turned off for the produc
17. Figure 2 9 A simplified version of the Soar algorithm Conflict impasse A conflict impasse arises if at least two values have conflicting better or worse preferences such as A is better than B and B is better than A for an operator and neither one is rejected prohibited or required Constraint failure impasse A constraint failure impasse arises if there is more than one required value for an operator or if a value has both a require and a prohibit preference These preferences represent constraints on the legal selections that can be made for a decision and if they conflict no progress can be made from the current situation and the impasse cannot be resolved by additional preferences No change impasse A no change impasse arises if a new operator is not selected during the decision procedure There are two types of no change impasses state no change and operator no change 2 6 IMPASSES AND SUBSTATES 25 State no change impasse A state no change impasse occurs when there are no acceptable or require preferences to suggest operators for the current state or all the acceptable values have also been rejected The decision procedure cannot select a new operator Operator no change impasse An operator no change impasse occurs when either a new operator is selected for the current state but no additional productions match during the application phase or a new operator is not selected during the next decision phase
18. Options d decision Run Soar for count decision cycles e elaboration Run Soar for count elaboration cycles o output Run Soar until the nth time output is generated by the agent Lim ited by the value of max nil output cycles p phase Run Soar by phases A phase is either an input phase proposal phase decision phase apply phase or output phase s self If other agents exist within the kernel do not run them at this time u update Sets a flag in the update event callback requesting that an environ ment updates This is the default if self is not specified n noupdate Sets a flag in the update event callback requesting that an environ ment does not update This is the default if self is specified f forever Run until halted by problem solving completion or until stopped by an interrupt count A single integer which specifies the number of cycles to run Soar i interleave Support round robin execution across agents at a finer grain than the run size parameter e elaboration p phase d decision o output Deprecated Options These may be reimplemented in the future 5 1 BASIC COMMANDS FOR RUNNING SOAR 89 operator Run Soar until the nth time an operator is selected state Run Soar until the nth time a state is selected Description The run command starts the Soar execution cycle or continues any execution that was te
19. The intended range of numeric preference values for avg mode is 0 100 The other combination option sum assigns a final value according to the rule e Add together any numeric preferences for the operator defaulting to 0 if there are none e Assign the operator the value e PreferenceSum AgentTemperature where AgentTemperature is a compile time constant currently set at 25 0 Any real numbered preference may be used in sum mode Once a value has been computed for each operator the next operator is selected probabilistically with each candidate operator s chance weighted by its computed value 132 CHAPTER 5 THE SOAR USER INTERFACE 5 4 11 o support mode Choose experimental variations of o support Synopsis o support mode 0 1121314 Options 0 Mode 0 is the base mode O support is calculated based on the structure of working memory that is tested and modified Testing an operator or oper ator acceptable preference results in state or operator augmentations being o supported The support computation is very complex see soar manual Not available through gSKI Mode 2 is the same as mode 0 except that all support is calculated the pro duction structure not from working memory structure Augmentations of operators are still o supported Mode 3 is the same as mode 2 except that operator elaborations adding attributes to operators now get i support even though you have to test the opera
20. dash dash greaterthan the production s actions and a closing curly brace Each element of a production is separated by white space Indentation and linefeeds are used by convention but are not necessary sp production name Documentation string type CONDITIONS gt ACTIONS An example production named blocks world propose move block is shown in Figure 3 2 This production proposes operators named move block that move blocks from one location to another The details of this production will be described in the following sections Conventions for indenting productions Productions in this manual are formatted using conventions designed to improve their readability These conventions are not part of the required syntax First the name of the production immediately follows the first curly bracket after the sp All conditions are aligned with the first letter after the first curly brace and attributes of an object are all aligned The arrow is indented to align with the conditions and actions and the closing curly brace follows the last action 40 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS 3 3 1 Production Names The name of the production is an almost arbitrary constant See Section 3 1 1 for a description of constants By convention the name describes the role of the production but functionally the name is just a label primarily for the use of the programmer A production name should never be a single letter follow
21. decisions phases 3 or decisions phases productions 4 or decisions phases productions wmes 5 or decisions phases productions wmes preferences The numerical arguments inclusively turn on all levels up to the number specified To use numerical arguments to turn off a level specify a number which is less than the level to be turned off For instance to turn off watching of productions specify watch 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 117 level 2 or 1 or 0 Numerical arguments are provided for shorthand convenience For more detailed control over the watch settings the named arguments should be used With no arguments this command prints information about the current watch sta tus i e the values of each parameter For the named arguments including the named argument turns on only that setting To turn off a specific setting follow the named argument with remove or 0 The named argument productions is shorthand for the four arguments default user justifications and chunks Examples The most common uses of watch are by using the numeric arguments which indicate watch levels To turn off all printing of Soar internals do any one of the following not all possibilities listed watch level 0 watch 1 0 watch N Although the level flag is optional its use is better form especially for complex arg lists watch level 5 emph OK watch 5 emph
22. desired S1 desired D1 0 102 CHAPTER 5 THE SOAR USER INTERFACE Support for S1 superstate set S1 superstate set nil Preferences for S1 operator acceptables 02 fill 03 fill Arch created wmes for S1 2 S1 superstate nil 1 S1 type state Input IO wmes for S1 3 S1 io I1 See Also 5 2 7 print Print items in working memory or production memory Synopsis print fFin production_name print alc D jlu fFin print i d lt depth gt identifier timetag pattern print s oS 5 2 EXAMINING MEMORY 103 Options Printing items in production memory ay call print the names of all productions currently loaded c chunks print the names of all chunks currently loaded D defaults print the names of all default productions currently loaded f full When printing productions print the whole production This is the default when printing a named production F filename also prints the name of the file that contains the pro duction i internal items should be printed in their internal form For productions this means leaving conditions in their re ordered rete net form j justifications print the names of all justifications currently loaded n name When printing productions print only the name and not the whole production This is the default when printing any category of productions as oppose
23. detects if a preference or working memory elmenet created in a substate is also linked to a superstate These working memory elements and preferences will not be removed when the im passe is resolved because they are still linked to a superstate and therefore they are called the results of the subgoal A result has either I support or O support the determination of support is described below A working memory element or preference will be a result if its identifier is already linked to a superstate A working memory element or preference can also become a result indirectly if after it is created and it is still in working memory or preference memory its identifier becomes linked to a superstate through the creation of another result For example if the problem solving in a state constructs an operator for a superstate it may wait until the operator structure is complete before creating an acceptable preference for the operator in the superstate The acceptable preference is a result because it was created in the state and is linked to the superstate and through the superstate is linked to the top level state The substructures of the operator then become results because the operator s identifier is now linked to the superstate z 3The original state is the top of the stack because as Soar runs this state created first will be at the top of the computer screen and substates will appear on the screen below the top level
24. explain backtraces c lt n gt prod_name Options no args List all productions that can be explained prod_name List all conditions and grounds for the chunk or justification c condition Explain why condition number n is in the chunk or justification Description This command provides some interpretation of backtraces generated during chunking The two most useful variants are explain backtraces prodname explain backtraces c n prodname The first variant prints a numbered list of all the conditions for the named chunk or justification and the ground which resulted in inclusion in the chunk justification A ground is a working memory element WME which was tested in the super goal Just knowing which WME was tested may be enough to explain why the chunk justification exists If not the second variant explain backtraces c n prodname where n is the condition of interest can be used to obtain a list of the productions which fired to obtain this condition in the chunk justification and the crucial WMEs tested along the way save backtraces mode must be on when a chunk or justification is created or no explanation will be available Calling explain backtraces with no argument prints a list of all chunks and justifications for which backtracing information is available Examples Examining the chunk chunk 65 d13 tie 2 generated in a water jug task soar gt explain backtraces chunk 65 d13 tie
25. lt s gt problem space blocks thing lt thing1 gt lt gt lt thing1l gt lt thing2 gt ontop lt ontop gt lt thing1 gt type block clear yes lt thing2 gt clear yes lt ontop gt top block lt thing1 gt pottom block lt gt lt thing2 gt gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt destination lt thing2 gt HHHHHHHEHHHHHHHHHRRAAHAA ARE HHH HHRRR RHEE RRR HH HARA HAAR H HR Make all acceptable move block operators also indifferent The conditions establish that 1 the state has an acceptable preference for an operator 2 the operator is named move block The actions 1 create an indifferent prefererence for the operator sp blocks world compare move block indifferent state lt s gt operator lt o gt lt o gt name move block gt lt s gt operator lt o gt 160 APPENDIX A THE BLOCKS WORLD PROGRAM HHHHHHHHHHAE AHHH HHHHAAAEHA AREER HHH RRR HH HARRAH AAR Apply a MOVE BLOCK operator There are two productions that are part of applying the operator Both will fire in parallel HHHHHHHRHHHHHHHHHRHAAHAA AREER HRR REAR EERE HHA HHA HARE HERR HHS HHHHHHAAHHHHHHHHHAHAAHAA ARE HHH HHHH REA A RARE HARRAH HAAR HERR Apply a MOVE BLOCK operator the block is no longer ontop of the thing it used to be ontop of This production is part of the application of a move block op
26. procedure learning and input and output 2 1 An Overview of Soar The design of Soar is based on the hypothesis that all deliberate goal oriented behavior can be cast as the selection and application of operators to a state A state is a representation of the current problem solving situation an operator transforms a state makes changes to the representation and a goal is a desired outcome of the problem solving activity As Soar runs it is continually trying to apply the current operator and select the next operator a state can have only one operator at a time until the goal has been achieved The selection and application of operators is illustrated in Figure 2 1 Soar has separate memories and different representations for descriptions of its cur rent situation and its long term knowledge In Soar the current situation including data from sensors results of intermediate inferences active goals and active opera tors is held in working memory Working memory is organized as objects Objects are described in terms of their attributes the values of the attributes may correspond to sub objects so the description of the state can have a hierarchical organization This need not be a strict hierarchy for example there s nothing to prevent two objects from being substructure of each other The long term knowledge which specifies how to respond to different situations in 6 CHAPTER 2 THE SOAR ARCHITECTURE Soar exe
27. than each other one candidate remaining no candidates remaining remaining candidates are Outcome of preference _resolution_ winner returned constraintfailure impasse winner returned none selected nochange impasse conflict impasse winner returned none selected nochange impasse ALL mutually indifferent winner will be chosen based on userselect setting remaining candidates are NOT mutually indifferent tie impasse Figure D 1 An illustration of the preference resolution process There are eight steps only five of these provide exits from the resolution process e Otherwise If there is more than one required candidate then a constraint failure impasse is recognized and preference semantics terminates by re turning the set of required candidates e Otherwise If there exists a required candidate that is also prohibited a constraint failure impasse with the required prohibited value is recognized 169 and preference semantics terminates e Otherwise The candidates are passed to AcceptableCollect AcceptableCollect This operation builds a list of operators for which there is an acceptable preference in preference memory This list of candidate operators is passed to the ProhibitFilter ProhibitFilter This filter removes the candidates that have prohibit prefer ences in memory The rest of the candidates are passed to the RejectFilter RejectFilter This filt
28. that may have additional substructure In semantic net terms if a value is a constant then it is a terminal node with no links if it is an identifier it is a nonterminal node One key concept of Soar is that working memory is a set which means that there can never be two elements in working memory at the same time that have the same identifier attribute value triple this is prevented by the architecture However it is possible to have multiple working memory elements that have the same identifier and attribute but that each have different values When this happens we say the attribute is a multi valued attribute which is often shortened to be multi attribute An object is defined by its augmentations and not by its identifier An identifier is simply a label or pointer to the object On subsequent runs of the same Soar program there may be an object with exactly the same augmentations but a different identifier and the program will still reason about the object appropriately Identifiers are internal markers for Soar they can appear in working memory but they never appear in a production There is no predefined relationship between objects in working memory and real objects in the outside world Objects in working memory may refer to real objects such as block A features of an object such as the color red or shape cube a relation between objects such as ontop classes of objects such as blocks etc The actual names of attr
29. 18 productions excised Source finished This can be disabled by using the d flag agent gt source demos mac mac soar d BOO RAK Source finished agent gt source demos mac mac soar d HAHAHAHAH AEA ER Hk Hk Hk Hk HKHH HHHH Source finished A list of excised productions is available using the v flag agent gt source demos mac mac soar v HK HEK HEK HEK HK Hk HK HE HK HK HE EK Hk Hk Hk Hk H H Total 18 productions sourced 18 productions excised Excised productions mac detect state success mac evaluate state failure more cannibals monitor move boat 5 6 SOAR I O COMMANDS 147 monitor state left A separate summary for each file sourced can be enabled using the a flag agent gt source demos mac mac soar a _firstload soar 0 productions sourced all_source soar 0 productions sourced ek goal test soar 2 productions sourced 4K monitor soar 3 productions sourced KOK search control soar 4 productions sourced top state soar 0 productions sourced elaborations_source soar 0 productions sourced _readme soar 0 productions sourced ek initialize mac soar 2 productions sourced FORK move boat soar 7 productions sourced mac_source soar 0 productions sourced mac soar 0 productions sourced Total 18 productions sourced Source finished Combining the a and v flag adds excised production names to the output for each file See Also cd dirs ls pushd popd 5 6 Soar I O Commands This
30. 8 de Seo wo Rs The Dependency Set in Soar 8 2 2 ee ee ee The algorithm for determining members of the GDS The GDS and WME data structures 0 4 168 vi LIST OF FIGURES Chapter 1 Introduction Soar has been developed to be an architecture for constructing general intelligent systems It has been in use since 1983 and has evolved through many different versions This manual documents the most current of these Soar version 8 6 Our goals for Soar include that it is to be an architecture that can be used to build systems that work on the full range of tasks expected of an intelligent agent from highly routine to extremely difficult open ended prob lems represent and use appropriate forms of knowledge such as procedural declara tive episodic and possibly iconic employ the full range of problem solving methods interact with the outside world and learn about all aspects of the tasks and its performance on those tasks In other words our intention is for Soar to support all the capabilities required of a general intelligent agent Below are the major principles that are the cornerstones of Soar s design 1 The number of distinct architectural mechanisms should be minimized In Soar there is a single representation of permanent knowledge productions a single representation of temporary knowledge objects with attributes and values a single mechanism for generating goals aut
31. Commands for Running Soar 2 Examining Memory 3 Configuring Trace Information and Debugging 4 Configuring Soar s Run Time Parameters 5 File System I O Commands 6 Soar I O commands 7 Miscellaneous Commands Each section begins with a summary description of the commands covered in that section including the role of the command and its importance to the user Commands are then described fully in alphabetical order The most accurate and up to date information on the syntax of the Soar User Interface is found online on the Soar Wiki at http winter eecs umich edu soarwiki Soar_Command_Line_Interface Throughout this chapter each function description includes a specification of its syntax and an example of its use For a concise overview of the Soar interface functions see the Function Summary and Index on page 185 This index is intended to be a quick reference into the commands described in this chapter 83 84 CHAPTER 5 THE SOAR USER INTERFACE Notation The notation used to denote the syntax for each user interface command follows some general conventions e The command name itself is given in a bold font e Optional command arguments are enclosed within square brackets and e A vertical bar separates alternatives e Curly braces are used to group arguments when at least one argument from the set is required e The commandline prompt that is printed by Soar is normally the agent name followe
32. FR A single production should not fulfill more than one of these roles except for propos ing an operator and creating an absolute preference for it Although productions are not declared to be of one type or the other Soar examines the structure of each production and classifies the rules automatically based on whether they propose and compare operators apply operators or elaborate the state 2 3 3 Production Actions and Persistence Generally actions of a production either create preferences for operator selection or create remove working memory elements For operator proposal and compari son a production creates preferences for operator selection These preferences should persist only as long as the production instantiation that created them continues to match When the production instantiation no longer matches the situation has changed making the preference no longer relevant Soar automatically removes the preferences in such cases These preferences are said to have support for instan tiation support Similarly state elaborations are simple inferences that are valid only so long as the production matches Working memory elements created as state 2 4 PREFERENCE MEMORY SELECTION KNOWLEDGE 19 elaborations also have I support and remain in working memory only as long as the production instantiation that created them continues to match working memory For example the set of relevant operators changes as the state change
33. Options n Maximum number of chunks allowed during a decision cycle Description The max chunks command is used to limit the maximum number of chunks that may be created during a decision cycle The initial value of this variable is 50 allowable settings are any integer greater than 0 The chunking process will end after max chunks chunks have been created even if there are more results that have not been backtraced through to create chunks and Soar will proceed to the next phase A warning message is printed to notify the user that the limit has been reached This limit is included in Soar to prevent getting stuck in an infinite loop during the chunking process This could conceivably happen because newly built chunks may match immediately and are fired immediately when this happens this can in turn lead to additional chunks being formed etc If you see this warning something is seriously wrong Soar is unable to guarantee consistency of its internal structures You should not continue execution of the Soar program in this situation stop and determine whether your program needs to build more chunks or whether you ve discovered a bug in your program or in Soar itself 5 4 6 max elaborations Limit the maximum number of elaboration cycles in a given phase Print a warning message if the limit is reached during a run Synopsis max elaborations n Options n Maximum allowed elaboration cycles must be
34. Summary of Soar Aliases and Functions Predefined Aliases 185 There are a number of Soar commands that are shorthand for other Soar commands Alias Summary Page Alias for help 86 a Alias for alias 151 aw Alias for add wme 148 chdir Alias for cd 137 d Alias for run d 1 runs by decision cycles 88 dir Alias for 1s 141 e Alias for run e 1 runs by elaboration cycles 88 eb Alias for explain backtraces 1 ex Alias for excise 85 exit Alias for quit 87 fc Alias for firing counts 108 gds_print Alias for gds print 95 h Alias for help 86 inds Alias for indifferent selection 124 init Alias for init soar 86 interrupt Alias for stop soar 92 is Alias for init soar 86 1 Alias for learn 125 man Alias for help 86 p Alias for the print command 102 pe Alias for print chunks 102 pr Alias for preferences 99 pw Alias for pwatch 109 rn Alias for rete net 144 rw Alias for remove wme 149 set default depth Alias for default wme depth 93 sn Alias for soarnews 154 ss Alias for stop soar 92 st Alias for stats 110 step Alias for run 1 88 stop Alias for stop soar 92 topd Alias for pwd 143 un Alias for alias d 151 unalias Alias for alias d 151 W Alias for watch 113 wmes Alias for print i 102 186 INDEX Summary of Soar Functions The following table lists the commands in Soar See the referenced page number for a complete description of each command Command Summary Page add wme Manually add
35. THE SYNTAX OF SOAR PROGRAMS print a production using the print command the production will not be represented using attribute path notation Negations and attribute path notation A negation may be used with attribute path notation in which case it amounts to a negated conjunction For example the production sp blocks negated conjunction example state lt s gt name top state lt s gt ontop lt on gt lt on gt bottom object lt bo gt lt bo gt type table gt lt s gt nothing ontop table true could be rewritten as sp blocks negated conjunction example state lt s gt name top state ontop bottom object type table gt lt s gt nothing ontop table true Multi valued attributes and attribute path notation Attribute path notation may also be used with multi valued attributes such as sp blocks world propose move block state lt s gt problem space blocks clear block lt blocki gt lt gt lt block1 gt lt block2 gt ontop lt ontop gt lt block1 gt type block lt ontop gt top block lt block1 gt pottom block lt gt lt block2 gt gt lt s gt operator lt o gt lt o gt name move block moving block lt blocki gt destination lt block2 gt Multi attributes and attribute path notation Note It would not be advisable to write the production in Figure 3 2 using attribute path notation as follo
36. When Soar interacts with an external environment it must make use of mechanisms that allow it to receive input from that environment and to effect changes in that environment An external environment may be the real world or a simulation input is usually viewed as Soar s perception and output is viewed as Soar s motor abilities Soar I O is accomplished via input functions and output functions Input functions are called at the start of every execution cycle and add elements directly to specific input structures in working memory These changes to working memory may change the set of productions that will fire or retract Output functions are called at the end of every execution cycle and are processed in response to changes to specific output structures in working memory An output function is called only if changes have been made to the output link structures in working memory The structures for manipulating input and output in Soar are linked to a predefined attribute of the top level state called the io attribute The io attribute has sub structure to represent sensor inputs from the environment called input links because these are represented in working memory Soar productions can match against input links to respond to an external situation Likewise the io attribute has substruc ture to represent motor commands called output links Functions that execute motor commands in the environment use the values on the output links to determi
37. a or b d disable off Turn all chunking off default E except Learning is on except as specified by RHS dont learn actions 6 only Chunking is on only as specified by RHS force learn actions 1 List Prints listings of dont learn and force learn states a all levels Build chunks whenever a subgoal returns a result Learning must be enabled b bottom up Build chunks only for subgoals that have not yet had any subgoals with chunks built Learning must be enabled Description The learn command controls the parameters for chunking Soar s learning mecha nism With no arguments this command prints out the current learning environ ment status If arguments are provided they will alter the learning environment as described in the options and arguments table The watch command can be used to provide various levels of detail when productions are learned Learning is disabled by default With the on flag chunking is on all the time With the except flag chunking is on but Soar will not create chunks for states that have had RHS dont learn actions executed in them With the only flag chunking is off but Soar will create chunks for only those states that have had RHS force learn actions executed in them With the off flag chunking is off all the time 126 CHAPTER 5 THE SOAR USER INTERFACE The only flag and its companion force learn RHS action allow Soar developers to tu
38. alias Define a new alias or command using existing commands and arguments edit production Fire event to Move focus in an open editor to this production input period For Soar7 mode controls the rate of input to the Soar agent 5 7 MISCELLANEOUS 151 soarnews Prints information about the current release srand Seed the random number generator time Uses a default system clock timer to record the wall time required while executing a command version Returns version number of Soar kernel 5 7 1 alias Define a new alias or command using existing commands and arguments Synopsis alias name cmd lt args gt alias Options No options Description This command defines new aliases by creating Soar procedures with the given name The new procedure can then take an arbitrary number of arguments which are post pended to the given definition and then that entire string is executed as a command The definition must be a single command multiple commands are not allowed The alias procedure checks to see if the name already exists and does not destroy existing procedures or aliases by the same name Existing aliases can be removed by using the unalias command With no arguments alias returns the list of defined aliases With only the name given alias returns the current definition Examples The alias wmes is defined as alias wmes print i If the user executes a command such as wmes superstat
39. allowed in preference mem ory 3 3 Production Memory Production memory contains productions which can be loaded in by a user typed in while Soar is running or sourced from a file or generated by chunking while Soar is running Productions both user defined productions and chunks may be examined using the print command described in Section 5 2 7 on page 102 Each production has three required components a name a set of conditions also called the left hand side or LHS and a set of actions also called the right hand side or RHS There are also two optional components a documentation string and a type Syntactically each production consists of the symbol sp followed by an opening curly brace the production s name the documentation string optional the production 3 3 PRODUCTION MEMORY 39 sp blocks world propose move block state lt s gt problem space blocks thing lt thing1 gt lt gt lt thing1l gt lt thing2 gt ontop lt ontop gt lt thing1 gt type block clear yes lt thing2 gt clear yes lt ontop gt top block lt thing1 gt pottom block lt gt lt thing2 gt gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt destination lt thing2 gt Figure 3 2 An example production from the example blocks world task type optional comments optional the production s conditions the symbol gt literally
40. also specify the absence of patterns in working memory For example the conditions could also specify that block A is not red or there are no red blocks on the table But since these are not needed for our example production there are no examples of negated conditions for now The order of the conditions of a production do not matter to Soar except that the first condition must directly test the state Internally Soar will reorder the conditions so that the matching process can be more efficient This is a mechanical detail that need not concern most users However you may print your productions to the screen or save them in a file if they are not in the order that you expected them to be it is likely that the conditions have been reordered by Soar 2 3 1 1 Variables in productions and multiple instantiations In the example production above the names of the blocks are hardcoded that is they are named specifically In Soar productions variables are used so that a production can apply to a wider range of situations The variables are bound to specific symbols in working memory elements by Soar s matching process A production along with a specific and consistent set of variable bindings is called an instantiation A production instantiation is consistent only if every occurrence of a variable is bound to the same value Since the same production may match multiple times each with different variable bindings several inst
41. and will be the same for repeated runs Even when a constant looks like an identifier it will not act like an identifier in terms of matching A constant is printed surrounded by vertical bars whenever there is a possibility of confusing it with an identifier G37 is a constant while G37 is an identifier To avoid possible confusion you should not use letter number combinations as constants or for production names 3 1 2 Objects Recall from Section 2 2 that all WME s that share an identifier are collectively called an object in working memory The individual working memory elements that make up an object are often called augmentations because they augment the object A template for an object in working memory is 3 1 WORKING MEMORY 35 identifier attribute 1 value 1 attribute 2 value 2 attribute 3 value 3 attribute n value n For example if you run Soar with the example blocks world program described in Appendix A after one elaboration cycle you can look at the top level state by using the print command soar gt print sl S1 io I1 ontop 02 ontop 03 ontop 01 problem space blocks superstate nil thing B3 thing T1 thing B1 thing B2 type state The attributes of an object are printed in alphabetical order to make it easier to find a specific attribute Working memory is a set so that at any time there are never duplicate versions of working memory elements However it
42. conflict cfailure snochange opnochange 108 CHAPTER 5 THE SOAR USER INTERFACE dcChunknum is the number of the chunk within that specific decision cycle 5 3 2 iring counts Print the number of times each production has fired Synopsis firing counts n firing counts production_names Options If given an option can take one of two forms an integer or a list of production names n List the top n productions If n is 0 only the productions which haven t fired are listed production_name For each production in production_names print how many times the production has fired Description The firing counts command prints the number of times each production has fired production names are given from most requently fired to least frequently fired With no arguments it lists all productions If an integer argument n is given only the top n productions are listed If n is zero 0 only the productions that haven t fired at all are listed If one or more production names are given as arguments only firing counts for these productions are printed Note that firing counts are reset by a call to init soar Examples This example prints the 10 productions which have fired the most times along with their firing counts firing counts 10 This example prints the firing counts of productions my first production and my second production firing counts my first production my second production
43. destination lt thing2 gt Notes on structured value notation e Attribute path notation and structured value notation are orthogonal and can be combined in any way A structured value can contain an attribute path or a structure can be given as the value for an attribute path e Structured value notation may also be combined with negations and with multi attributes e Structured value notation may not be used in the actions of productions 3 3 6 The action side of productions or RHS The action side of a production also called the right hand side or RHS of the production consists of individual actions that can e Add new elements to working memory e Remove elements from working memory e Create preferences e Perform other actions When the conditions of a production match working memory the production is said to be instantiated and the production will fire during the next elaboration cycle Firing the production involves performing the actions using the same variable bindings that formed the instantiation 3 3 PRODUCTION MEMORY 57 3 3 6 1 Variables in Actions Variables can be used in actions A variable that appeared in the condition side will be replaced with the value that is was bound to in the condition A variable that appears only in the action side will be bound to a new identifier that begins with the first letter of that variable e g lt o gt might be bound to 0234 This symbol is guaranteed to be uni
44. does not increase the dependency set nor do O supported results Thus only subgoals that involve the creation of internal O support working memory elements risk regeneration and then only when the basis for the creation of those elements changes Substate Removal Whenever a substate is removed all working memory elements and preferences that were created in the substate that are not results are removed from working memory In Figure 2 10 state 3 will be removed from working memory when the impasse that created it is resolved that is when sufficient preferences have been generated so that one of the operators for state S2 can be selected When state S3 is removed operator 09 will also be removed as will the acceptable preferences for 07 08 and 09 and the impasse attribute and choices augmentations of state 3 These working memory elements are removed because they are no longer linked to the subgoal stack The acceptable preferences for operators 04 05 and 06 remain in working memory They were linked to state S3 but since they are also linked to state 2 they will stay in working memory until S2 is removed or until they are retracted or rejected 2 7 LEARNING 31 2 6 5 Soar s Cycle With Substates When there are multiple substates Soar s cycle remains basically the same but has a few minor changes The first change is that during the decision procedure Soar will detect impasses and create new substates For example
45. following the proposal phase the decision phase will detect if a decision cannot be made given the current preferences If an impasse arises a new substate is created and added to working memory The second change when there are multiple substates is that at each phase Soar goes through the substates from oldest highest to newest lowest completing any necessary processing at that level for that phase before doing any processing in the next substate When firing productions for the proposal or application phases Soar processes the firing and retraction of rules starting from those matching the oldest substate to the newest Whenever a production fires or retracts changes are made to working memory and preference memory possibly changing which productions will match at the lower levels productions firing within a given level are fired in parallel simulated Productions firings at higher levels can resolve impasses and thus eliminate lower states before the productions at the lower level ever fire Thus whenever a level in the state stack is reached all production activity is guaranteed to be consistent with any processing that has occurred at higher levels 2 7 Learning When an operator impasse is resolved it means that Soar has through problem solving gained access to knowledge that was not readily available before Therefore when an impasse is resolved Soar has an opportunity to learn by summarizing and generalizing the p
46. for the best preference 2 4 PREFERENCE MEMORY SELECTION KNOWLEDGE 21 Indifferent An indifferent preference states that there is positive knowledge that it does not matter which value is selected This may be a binary preference to say that two values are mutually indifferent or a unary preference to say that a single value is as good or as bad a choice as other expected alternatives When indifferent preferences are used to signal that it does not matter which operator is selected by default Soar chooses randomly from among the alter natives The indifferent selection function can be used to change this behavior as described on page 124 in Chapter 5 Numeric Indifferent number A numeric indifferent preference is used to bias the random selection from mutually indifferent values This preference in cludes a unary indifferent preference so an operator with a numeric indifferent preference will not force a tie impasse Additionally the preference weights the operator s probability of being selected according to the number given For instance given the preferences lt s gt operator lt 01 gt 40 lt s gt operator lt o2 gt 10 the operator bound to lt o1 gt would be more likely to be selected whereas lt s gt operator lt ol gt lt s gt operator lt 02 gt would give equal probability to the two choices There are two schemes for com bining multiple numeric indifferent preferences
47. functions allow productions to create side effects other than changing working memory The RHS functions are described below organized by the type of side effect they have 60 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS 3 3 6 7 Stopping and pausing Soar halt Terminates Soar s execution and returns to the user prompt A halt action irreversibly terminates the running of a Soar program It should not be used if Soar is to be restarted see the interrupt RHS action below sp gt halt interrupt Executing this function causes Soar to stop at the end of the current phase and return to the user prompt This is similar to halt but does not terminate the run The run may be continued by issuing a run command from the user interface The interrupt RHS function has the same effect as typing stop soar at the prompt except that there is more control because it takes effect exactly at the end of the phase that fires the production sp gt interrupt Soar execution may also be stopped immediately before a production fires using the interrupt directive This functionality is called a matchtime interrupt and is very useful for debugging See Section 5 1 6 on Page 90 for more information sp production name interrupt gt 3 3 6 8 Text input and output The function write is provided as a production action to do simple output of text in Soar Soar applications that do extensive input and output of text should u
48. gds print is useful for examining the goal dependecy set when subgoals seem to be disappearing unexpectedly default wme depth is related to the print command internal symbols is not often used but is helpful when debugging Soar extensions or trying to locate memory leaks 5 2 1 default wme depth Set the level of detail used to print WMEas 94 CHAPTER 5 THE SOAR USER INTERFACE Synopsis default wme depth depth Options depth A non negative integer Description The default wme depth command reflects the default depth used when working memory elements are printed using the print command or wmes alias The default value is 1 When the command is issued with no arguments default wme depth returns the current value of the default depth When followed by an integer value default wme depth sets the default depth to the specified value This default depth can be overridden on any particular call to the print or wmes command by explicitly using the depth flag e g print depth 10 args By default the print command prints objects in working memory not just the indi vidual working memory element To limit the output to individual working memory elements the internal flag must also be specified in the print command Thus when the print depth is O by default Soar prints the entire object which is the same behavior as when the print depth is 1 But if internal is also specified then a depth of 0 prints ju
49. groups the test in these conditions together This grouping allows for negated tests of more than one working memory element at a time In the example below the state is tested to ensure that it does not have an object on the table sp blocks negated conjunction example state lt s gt name top state lt s gt ontop lt on gt lt on gt bottom object lt bo gt lt bo gt type table gt lt s gt nothing ontop table true When using negated conjunctions of conditions the production has nested curly braces One set of curly braces delimits the production while the other set delimits the conditions to be conjunctively negated If only the last condition lt bo gt type table were negated the production would match only if the state had an ontop relation and the ontop relation had a bottom object but the bottom object wasn t a table Using the negated conjunction the production will also match when the state has no ontop augmentation or when it has an ontop augmentation that doesn t have a bottom object augmentation The semantics of negated conjunctions can be thought of in terms of mathematical logic where the negation of A A BAC A AA BAC can be rewritten as 4A V 4B V C That is not A and B and C becomes not A or not B or not C 3 3 5 8 Multi valued attributes An object in working memory may have multiple augmentations that specify the same attribu
50. id operator value unary indifferent id operator value value2 binary indifferent id operator value number numeric indifferent The identifier and value will always be variables such as lt s1 gt operator lt 01 gt gt lt 02 gt The preference notation appears similar to the predicate tests that appear on the left hand side of productions but has very different meaning Predicates cannot be used on the right hand side of a production and you cannot restrict the bindings of variables on the right hand side of a production Such restrictions can happen only in the conditions Also notice that the symbol is optional when specifying acceptable preferences in the actions of a production although using this symbol will make the semantics of 3 3 PRODUCTION MEMORY 59 your productions clearer in many instances The symbol will always appear when you inspect preference memory with the preferences command Productions are never needed to delete preferences because preferences will be re tracted when the production no longer matches Preferences should never be created by operator application rules and they should always be created by rules that will give only I support to their actions 3 3 6 5 Shorthand notations for preference creation There are a few shorthand notations allowed for the creation of operator preferences on the right hand side of productions Acceptable preferences do not n
51. is added to working memory The names of identifiers are created by Soar and consist of a single uppercase letter followed by a string of digits such as G37 or 022 The Soar user interface will also allow users to specify identifiers using lowercase letters for example when using the print command But internally they are actually uppercase letters Constants There are three types of constants integers floating point and sym bolic constants e Integer constants numbers The range of values depends on the machine and implementation you re using but it is at least 2 billion 2 billion e Floating point constants numbers The range depends on the machine and implementation you re using e Symbolic constants These are symbols with arbitrary names A constant can use any combination of letters digits or amp lt gt _ Other characters such as blank spaces can be included by surrounding the complete constant name with vertical bars This is a constant The vertical bars aren t part of the name they re just notation A vertical bar can be included by prefacing it with a backslash inside surrounding vertical bars O0dd symbo1 name Identifiers should not be confused with constants although they may look the same identifiers are generated by the Soar architecture at runtime and will not necessarily be the same for repeated runs of the same program Constants are specified in the Soar program
52. lt lt gt gt 44 50 lt 43 lt gt 43 lt gt 43 43 58 169 gt see best preference 43 58 168 gt 43 58 carat symbol 33 58 168 30 acceptable preference 48 168 action side of production 56 action side grammar 164 add wme 148 alias 151 arithmetic operations 61 attribute 8 14 33 34 multi valued attribute 35 attribute preferences mode 121 augmentation see working memory element backtracing 77 78 best preference see best preference 168 better preference 168 bottom up chunking 76 capitalize symbol 64 carriage return line feed 61 cd 137 chunk 31 overgeneral 28 chunk name format 107 chunking see learning 75 actions 77 bottom up 76 conditions 78 79 creation 75 determining actions 77 determining conditions 78 duplicate chunks 76 incorrect chunks 80 negated conditions 77 81 ordering conditions 79 overgeneral 80 refractory inhibition 79 variablization 79 when active 75 clog 138 cmd 65 command to file 139 comments 41 compute 61 condition acceptable preference 48 condition side 41 condition side grammar 163 Conditions 42 conflict impasse 24 67 conjunctive conditions 45 negation 47 constant 34 164 constraint failure impasse 24 67 167 crlf 61 decision cycles 111 procedure 20 66 167 decision cycle 7 22 pseudo code 24 decision procedure 7 22 default wme depth 93 desirability
53. lt a 1 gt sue lt a 1 gt sally 3 3 5 11 Attribute path notation Often variables appear in the conditions of productions only to link the value of one attribute with the identifier of another attribute Attribute path notation provides a shorthand so that these intermediate variables do not need to be included Syntactically path notation lists a sequence of attributes separated by dots after the in a condition For example using attribute path notation the production sp blocks world monitor move block state lt s gt operator lt o gt lt o gt name move block moving block lt block1 gt destination lt block2 gt lt block1 gt name lt blocki name gt lt block2 gt name lt block2 name gt gt write crlf Moving Block lt blocki name gt to lt block2 name gt could be written as sp blocks world monitor move block state lt s gt operator lt o gt lt o gt name move block moving block name lt blocki name gt destination name lt block2 name gt gt write crlf Moving Block lt block1i name gt to lt block2 name gt Attribute path notation yields shorter productions that are easier to write less prone to errors and easier to understand When attribute path notation is used Soar internally expands the conditions into the multiple Soar objects creating its own variables as needed Therefore when you 52 CHAPTER 3
54. mode 3 does not notice that this condition is true This is a bug which is unlikely to be fixed since users are encouraged to use mode 4 165 166 APPENDIX C THE CALCULATION OF O SUPPORT sp elaborate state operator name state lt s gt superstate lt s1 gt lt s1 gt operator lt o gt lt o gt name lt name gt gt lt s gt name something the RHS action gets i support Of course the state bound to lt s gt is destroyed when lt si gt operator lt o gt retracts so o support would make little difference On the other hand the production sp operator superstate xapplication state lt s gt superstate lt s1 gt lt s gt operator lt o gt lt o gt name lt name gt gt lt s1 gt sub operator name lt name gt gives o support to its RHS action which remains after the substate bound to lt s gt is destroyed There is a third condition that determines support and it is in this condition that modes 3 amp 4 differ An extension of condition 1 is that operator augmentations should always receive i support Soar has been written to recognize augmentations directly off the operator ie lt o gt augmentation value and to attempt to give them i support However there was some confusion about what to do about a production that simultaneously tests an operator doesn t propose an operator adds an operator augmentation and adds a non operator augmentation such as
55. name Options No options Description This command undefines a previously created alias This command takes exactly one argument the name of the alias to remove Use the alias command by itself to list all defined aliases Examples unalias varprint Default Aliases Alias Maps to un unalias height See Also alias 156 CHAPTER 5 THE SOAR USER INTERFACE 5 7 8 version Synopsis version Options No options Description This command gives version information about the current Soar kernel It returns the version number itself which can then be stored by the agent or the application Appendix A The Blocks World Program HHEFHHHHHHHEEHHHEEHEEAHHAEEHEEA HAAR HEEHEHREERHEE HARE HHAEHEHAEEHHAA HEHEHE REE HHH File blocks soar Original author s John E Laird lt laird eecs umich edu gt Organization University of Michigan AI Lab Created on 15 Mar 1995 13 53 46 Last Modified By Clare Bates Congdon lt congdon eecs umich edu gt Last Modified On 17 Jul 1996 16 35 14 Soar Version sae HHH Description A new simpler implementation of the blocks world HHH with just three blocks being moved at random HHH Notes CBC 6 27 Converted to Tcl syntax HHH CBC 6 27 Added extensive comments HHHHHHHEHHHHHHHHERHAAHHA ARE HHRR RRA A RRR HHA HARARE HERR HHH HHHHHHHHHHAR EHH HHHHHHHAAAEHA AEE HERRERA RRR A AAR Create the initial state with
56. number of nil output cycles output cy cles that put nothing on the output link allowed when running using run til output run output If n is not given this command prints the current number of nil output cycles allowed If n is given it must be a positive integer and is used to reset the maximum number of allowed nil output cycles max nil output cycles controls the maximum number of output cycles that gen erate no output allowed when a run out command is issued After this limit has been reached Soar stops The default initial setting of n is 15 Examples The command issued with no arguments returns the max empty output cycles al lowed 130 CHAPTER 5 THE SOAR USER INTERFACE max nil output cycles to set the maximum number of empty output cycles in one phase to 25 max nil output cycles 25 See Also run 5 4 9 multi attributes Declare a symbol to be multi attributed Synopsis multi attributes symbol n Options symbol Any Soar attribute n Integer gt 1 estimate of degree of simultaneous values for attribute Description This command declares the given symbol to be an attribute which can take on multiple values The optional n is an integer gt 1 indicating an upper limit on the number of expected values that will appear for an attribute If n is not specified the value 10 is used for each declared multi attribute More informed values will tend to result in greater effi
57. object bound to lt p1 gt type father lt p1 gt type father A negation can be used within an object with many attribute value pairs by having it precede a specific attribute lt p1 gt name john type father spouse lt p2 gt In that example the condition would match if there is a working memory element that matches lt p1 gt name john and another that matches lt pi gt spouse lt p2 gt but is no working memory element that matches lt p1 gt type father when p1 is bound to the same identifier On the other hand the condition lt p1 gt name john type father spouse lt p2 gt would match only if there is no object in working memory that matches all three attribute value tests Example Production sp default evaluate object state lt ss gt operator lt so gt lt so gt type evaluation superproblem space lt p gt lt p gt default state copy no gt lt so gt default state copy yes Notes One use of negated conditions to avoid is testing for the absence of the working memory element that a production creates with I support this would lead to an 3 3 PRODUCTION MEMORY 47 infinite loop in your Soar program as Soar would repeatedly fire and retract the production 3 3 5 7 Negated conjunctions of conditions Conditions can be grouped into conjunctive sets by surrounding the set of conditions with and The production compiler
58. output cycles Limit the maximum number of decision cycles 129 memories Print memory usage for production matches 98 INDEX 187 Command Summary Page multi attributes Declare multi attributes so as to increase Rete 130 matching efficiency numeric indifferent mode Select method for combining numeric prefer 131 ences o support mode Choose experimental variations of o support 132 popd Pop a directory off of the directory stack chang 142 ing to it preferences Examine items in preference memory 99 print Print items in working memory or production 102 memory production find Find productions that contain a given pattern 105 pushd Push a directory onto the directory stack chang 143 ing to it pwatch Trace firings and retractions of specific produc 109 tions pwd Print the current working directory 143 quit Close log file terminate Soar and return user 87 to the operating system remove wme Manually remove an element from working 149 memory rete net Save the current Rete net or restore a previous 144 one run Begin Soar s execution cycle 88 save backtraces Save trace information to explain chunks and 132 justifications set library location Set the top level directory containing de 145 mos help etc soar8 Toggle between Soar 8 methodology and Soar 7 134 methodology soarnews Print information about the current release of 154 Soar source Load and evaluate the contents of a file 145 sp Create a producti
59. preference 78 80 dirs 140 181 182 disjunction of constants 44 disjunctions of attributes 50 dont learn 65 dot notation 51 echo 141 edit production 152 elaboration cycles 111 phase 67 excise 85 exec 64 exhaustion 67 76 81 explain backtraces 121 firing counts 108 float 62 floating point constants 34 floating point number 61 force learn 66 GDS 171 gds print 95 goal examples 67 representation 8 result see result stack 25 subgoal 22 25 31 termination 28 67 grammar 163 grammar action side 164 grammar condition side 163 halt 60 help 86 I support 18 of result 28 i support 165 I O 11 32 68 input functions 69 input links 69 io attribute 69 output functions 69 output links 69 identifier 14 33 34 37 variablization of 79 impasse 7 22 66 conflict 23 24 INDEX constraint failure 23 24 elimination 28 examples 67 no change 23 25 operator no change 25 resolution 28 67 state no change 25 tie 23 24 types 67 incorrect chunks 80 indifferent selection 20 124 init soar 86 input period 153 int 62 integer 34 interface 83 internal symbols 95 interrupt 60 item attribute 67 justification 28 creation 28 overgeneral 28 learn 75 125 learning 31 75 overgeneral 28 LHS of production 41 link 14 37 linked chunk action 77 Linux 4 Is 141 Macintosh 4 make constant symbol 63 matcher 79 matches
60. production should be considered a default production default or a chunk chunk or may specify that a production should be given O support o support or I support i support Users are discouraged from using these types These types are described in Section 5 1 6 which begins on Page 90 There is one additional flag interrupt which can be placed at this location in a production However this flag does not specify a production type but is a signal that the production should be marked for special debugging capabilities For more information see Section 5 1 6 on Page 90 3 3 PRODUCTION MEMORY 41 3 3 4 Comments optional Productions may contain comments which are not stored in Soar when the production is loaded and are therefore not printed out by the print command A comment is begun with a pound sign character and ends at the end of the line Thus everything following the is not considered part of the production and comments that run across multiple lines must each begin with a For example sp blocks world propose move block state lt s gt problem space blocks thing lt thing1 gt lt gt lt thing1 gt lt thing2 gt ontop lt ontop gt lt thing1 gt type block clear yes lt thing2 gt clear yes lt ontop gt top block lt thing1 gt pottom block lt gt lt thing2 gt gt lt s gt operator lt o gt lt o gt name move block you can also use in
61. section describes the commands used to manage Soar s Input Output I O sys tem which provides a mechanism for allowing Soar to interact with external systems such as a computer game environment or a robot Soar I O functions make calls to add wme and remove wme to add and remove ele ments to the io structure of Soar s working memory The specific commands described in this section are Summary 148 CHAPTER 5 THE SOAR USER INTERFACE add wme Manually add an element to working memory remove wme Manually remove an element from working memory These commands are used mainly when Soar needs to interact with an external en vironment Users might take advantage of these commands when debugging agents but care should be used in adding and removing wmes this way as they do not fall under Soar s truth maintenance system 5 6 1 add wme Manually add an element to working memory Synopsis add wme id attribute value Options id Must be an existing identifier Leading on attribute is optional attribute Attribute can be any Soar symbol Use to have Soar create a new identifier value Value can be any soar symbol Use to have Soar create a new identifier If the optional preference is specified its value must be accept able Description Manually add an element to working memory add wme is often used by an input function to update Soar s information about the
62. soar stop stop soar 5 2 EXAMINING MEMORY 93 See Also Tun Warnings If the graphical interface doesn t periodically do an update of flush the pending I O then it may not be possible to interrupt a Soar agent from the command line 5 2 Examining Memory This section describes the commands used to inspect production memory working memory and preference memory to see what productions will match and fire in the next Propose or Apply phase and to examine the goal dependency set These commands are particularly useful when running or debugging Soar as they let users see what Soar is thinking The specific commands described in this section are Summary default wme depth Set the level of detail used to print WME s gds print Print the WMEs in the goal dependency set for each goal internal symbols Print information about the Soar symbol table matches Print information about the match set and partial matches memories Print memory usage for production matches preferences Examine items in preference memory print Print items in working memory or production memory production find Find productions that contain a given pattern Of these commands print is the most often used and the most complex followed by matches and memories preferences is used to examine which candidate op erators have been proposed production find is especially useful when the number of productions loaded is high
63. state and modifies the state Thus a working memory element receives O support if it is for an aug mentation of the current state or substructure of the state and the conditions of the instantiation that created it test augmentations of the current operator When productions are matched all productions that have their conditions met fire creating or removing working memory elements Also working memory elements and preferences that lose support are removed from working memory Thus several new working memory elements and preferences may be created and several existing working memory elements and preferences may be removed at the same time Of course all this doesn t happen literally at the same time but the order of firings and retractions is unimportant and happens in parallel from a functional perspective 2 4 Preference memory Selection Knowledge The selection of the current operator is determined by the preferences in preference memory Preferences are suggestions or imperatives about the current operator or information about how suggested operators compare to other operators Preferences refer to operators by using the identifier of a working memory element that stands for the operator After preferences have been created for a state the decision procedures evaluates them to select the current operator for that state 20 CHAPTER 2 THE SOAR ARCHITECTURE For an operator to be selected there will be at least one prefere
64. symbol in between In the example production in Figure 3 2 there are seven variables lt s gt lt clear1 gt lt clear2 gt lt ontop gt lt block1 gt lt block2 gt and lt o gt The following table gives examples of legal and illegal variable names Legal variables Illegal variables lt s gt lt gt lt 1 gt lt 1 lt variable1 gt variable gt lt abc1 gt lt a b gt 3 3 5 3 Predicates for values A test for an identifier attribute or value in a condition whether constant or variable can be modified by a preceding predicate There are six predicates that can be used lt gt lt gt lt lt gt gt 2 Predicate Semantics of Predicate lt gt Not equal Matches anything except the value immediately following it lt gt Same type Matches any symbol that is the same type identifier integer floating point non numeric constant as the value immediately following it lt Numerically less than the value immediately following it lt Numerically less than or equal to the value immediately following it gt Numerically greater than or equal to the value immediately following it gt Numerically greater than the value immediately following it The following table shows examples of legal and illegal predicates 44 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS Legal predicates Illegal predicates gt lt valuex gt gt gt l
65. than operator B at this particular time or a preference may say that operator A is the best thing to do at this particular time 2 1 6 Selecting a single operator Soar attempts to select a single operator based on the preferences available for the candidate operators There are four different situations that may arise 1 The available preferences unambiguously prefer a single operator 2 The available preferences suggest multiple operators and prefer a subset that can be selected from randomly 3 The available preferences suggest multiple operators but neither case 1 or 2 above hold 4 The available preferences do not suggest any operators In the first case the preferred operator is selected In the second case one of the subset is selected randomly In the third and fourth cases Soar has reached an impasse in problem solving and a new substate is created Impasses are discussed in Section 2 6 In our blocks world example the second case holds and Soar can select one of the operators randomly 2 1 7 Applying the operator An operator applies by making changes to the state the specific changes that are appropriate depend on the operator and the current state There are two primary approaches to modifying the state indirect and direct Indirect changes are used in Soar programs that interact with an external environment The Soar program sends motor commands to the external environment and monitors the exte
66. the selection of the current operator could change Whenever operator preferences change the preferences are re evaluated and if a different operator selection would be made then the current operator augmentation of the state is immediately re moved However a new operator is not selected until the next decision phase when all knowledge has had a chance to be retrieved 2 6 Impasses and Substates When the decision procedure is applied to evaluate preferences and determine the operator augmentation of the state it is possible that the preferences are either incomplete or inconsistent The preferences can be incomplete in that no acceptable operators are suggested or that there are insufficient preferences to distinguish among acceptable operators The preferences can be inconsistent if for instance operator A is preferred to operator B and operator B is preferred to operator A Since preferences are generated independently from different production instantiations there is no guarantee that they will be consistent 2 6 IMPASSES AND SUBSTATES 23 Decision Cycle P Decision 2 Decision 3 Elaboration Phase Decision Phase Quiescence El ion Ph Elaboration Cycle aboration Phase Decision Phase 7 Decision Phase Preference Working Memory Quiescence Phase Phase no more 1 all opera ee are considere newly instantiated 1 all non operator poa productions fire preferences are considered to fire a 2 the preferences are
67. the table to red or blue sp blocks example production conditions state operator lt o gt table lt t gt lt o gt name move block lt t gt type table color lt lt red blue gt gt gt 3 3 PRODUCTION MEMORY 45 Note Disjunctions of complete conditions are not allowed in Soar Multiple similar pro ductions fulfill this role 3 3 5 5 Conjunctions of values A test for an identifier attribute or value in a condition may include a conjunction of tests all of which must hold for there to be a match Syntactically conjuncts are contained within curly braces i e and The follow ing table shows some examples of legal and illegal conjunctive tests Legal conjunctions Illegal conjunctions lt lt a gt gt lt b gt lt x gt lt lt a gt lt b gt lt x gt gt lt y gt gt gt lt b gt lt gt lt x gt lt y gt lt lt ABC gt gt lt x gt lt gt lt x gt gt lt y gt lt lt 1 2 3 4 gt gt lt z gt ASA AAS Because those examples are a bit difficult to interpret let s go over the legal examples one by one to understand what each is doing In the first example the value must be less than or equal to the value bound to variable lt a gt and greater than or equal to the value bound to variable lt b gt In the second example the value is bound to the variable lt x gt which must also be greater than the value bound
68. this way sp gt write The log of lt x gt is exec log lt x gt where log is a registered user defined function cmd Used to call built in Soar commands Spaces are inserted between concate nated arguments For example the production sp gt write cmd print depth 2 lt s gt will have the effect of printing the object bound to lt s gt to depth 2 3 3 6 12 Controlling learning Soar s learning mechanism called Chunking is described in Chapter 4 The following two functions are provided as RHS actions to assist in development of Soar programs they are not intended to correspond to any theory of learning in Soar This functionality is provided as a development tool so that learning may be turned off in specific problem spaces preventing otherwise buggy behavior The dont learn and force learn RHS actions are to be used with specific settings for the learn command see page 125 Using the learn command learning may be set to one of on off except or only learning must be set to except for the dont learn RHS action to have any effect and learning must be set to only for the force learn RHS action to have any effect 66 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS dont learn When learning is set to except by default chunks can be formed in all states the dont learn RHS action will cause learning to be turned off for the specified state sp turn learning off state lt
69. to variable lt y gt In the third example the value must not be equal to the value bound to variable lt x gt and should be bound to variable lt y gt Note the importance of order when using conjunctions with predicates in the second example the predicate modifies lt y gt but in the third example the predicate modifies lt x gt In the fourth example the value must be one of A B or C and the second conjunctive test binds the value to variable lt x gt In the fifth example there are four conjunctive tests First the value must be the same type as the value bound to variable lt x gt Second the value must be greater than the value bound to variable lt y gt Third the value must be equal to 1 2 3 or 4 Finally the value should be bound to variable lt z gt In Figure 3 2 a conjunctive test is used for the thing attribute in the first condition 46 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS 3 3 5 6 Negated conditions In addition to the positive tests for elements in working memory conditions can also test for the absence of patterns A negated condition will be matched only if there does not exist a working memory element consistent with its tests and variable bindings Thus it is a test for the absence of a working memory element Syntactically a negated condition is specified by preceding a condition with a dash i e ee For example the following condition tests the absence of a working memory element of the
70. 2 sp chunk 65 d13 tie 2 state lt s2 gt name water jug jug lt n4 gt jug lt n3 gt state lt si gt name water jug desired lt d1 gt operator lt o1 gt jug lt n1 gt jug lt n2 gt lt s2 gt desired lt d1 gt lt ol gt name pour into lt ni gt jug lt n2 gt lt ni gt volume 3 contents 0 lt si gt problem space lt p1 gt 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 123 lt pi gt name water jug lt n4 gt volume 3 contents 3 lt n3 gt volume 5 contents 0 lt n2 gt volume 5 contents 3 gt lt s3 gt operator lt 01 gt OON A TPWNH FE NNPPRP RP PRP BBB FOWMO ON OD TAFPWNHEFH CO 22 state lt s2 gt name water jug state lt si gt name water jug lt s1 gt desired lt d1 gt lt s2 gt desired lt d1 gt lt s1 gt operator lt 01 gt lt 01 gt name pour lt o1 gt into lt n1 gt lt n1 gt volume 3 lt ni gt contents 0 lt s1 gt jug lt n1 gt lt s1 gt problem space lt p1 gt lt p1 gt name water jug lt s2 gt jug lt n4 gt lt n4 gt volume 3 lt xn4 gt contents 3 lt s2 gt jug lt n3 gt lt n3 gt volume 5 lt n3 gt contents 0 lt si gt jug lt n2 gt lt n2 gt volume 5 lt n2 gt contents 3 lt 01 gt jug lt n2 gt Further examining condition 21 Gr
71. 96 max chunks 126 max elaborations 127 max memory usage 128 max nil output cycles 129 memories 98 motor commands see I O multi attribute see multi valued attribute multi attributes 130 multi valued attribute 15 47 79 necessity preference 80 negated INDEX conditions 46 81 conjunctions 47 negated conditions 77 no change impasse 25 67 not equal test 43 numeric comparisons 43 numeric indifferent mode 131 O support 18 of result 28 reject 19 o support 165 o support mode 132 object 36 37 Operating System 4 operator application 11 comparison 9 proposal 9 representation 8 selection 11 support 18 operator no change impasse 25 ordering chunk conditions 79 overgeneral chunk 78 80 path notation 51 persistence 18 20 165 Personal Computer 4 popd 142 predicates 43 preference 19 36 58 acceptable 20 21 36 168 acceptable as condition 48 best 20 168 better 20 168 indifferent 20 numeric indifferent 21 persistence see persistence prohibit 21 78 80 168 reject 20 168 require 21 78 80 167 semantics 20 syntax 38 worse 20 168 worst 20 169 preference memory 19 syntax 38 preferences 99 167 183 print 102 problem solving external 11 functions 6 internal 11 problem space 12 representation 8 production 7 16 condition 41 firing 16 instantiation 17 LHS 41 match 7 RHS 56 roles 18 structured values 55 syntax 38 produ
72. B and C on a table the operators move one block at a time to another location on top of another block 8 CHAPTER 2 THE SOAR ARCHITECTURE al B Mm Initial State Goal Figure 2 2 The initial state and goal of the blocks world task or onto the table and the goal is to build a tower with A on top B in the middle and C on the bottom The initial state and the goal are illustrated in Figure 2 2 The Soar code for this task is included in Appendix A You do not need to look at the code at this point The operators in this task move a single block from its current location to a new location each operator is represented with the following information e the name of the block being moved e the current location of the block the thing it is on top of e the destination of the block the thing it will be on top of The goal in this task is to stack the blocks so that C is on the table with block B on block C and block A on top of block B 2 1 3 Representation of States Operators and Goals The initial state in our blocks world task before any operators have been proposed or selected is illustrated in Figure 2 3 A state can have only one operator at a time and the operator is represented as substructure of the state A state may also have as substructure a number of potential operators that are in consideration however these suggested operators should not be confused with the curr
73. ENCY SET PRIMER The role of the GDS in agent design The GDS places some design time constraints on operator implementation These constraints are e Operator actions that are used to remember a previous state situation should be asserted in the top state e All operator elaborations should be i supported e Any operator with local actions should be designed to be re entrant This section describes these issues Soar says any operator effect is o supported regardless of whether that assertion is entailed by the current situation or whether it reflects an assumption about it The GDS adds additional needed constraint Because any context dependencies for subgoal o supported assertions will be added to the GDS the developer must decide if an o supported element should be represented in a substate or the top state This decision is straightforward if the functional role of the persistent element is considered Four important capabilities that require persistence are 1 Reasoning hypothetically Some assertions may need to reflect hypothet ical states Such assertions are assumptions because a hypothetical inference cannot always be grounded in the current context In other problem solvers with truth maintenance only assumptions are persistent 2 Reasoning non monotonically Sometimes the result of an inference changes one of the assertions on which the inference is dependent As an ex ample consider the task of counting Ea
74. O support or I support by using these commands regardless of the structure of the conditions and actions of the produc tion this is not proper coding style The o support and no support flags are included to help with debugging but should not be used in a standard Soar program Examples sp blocks create problem space This creates the top level space state lt si gt superstate nil CHAPTER 5 THE SOAR USER INTERFACE lt s1 gt name solve blocks world problem space lt p1 gt lt p1 gt name blocks world 92 gt See Also excise learn watch 5 1 7 stop soar Pause Soar Synopsis stop soar s reason string Options s self Stop only the soar agent where the command is issued All other agents continue running as previously specified reason string An optional string which will be printed when Soar is stopped to indicate why it was stopped If left blank no message will be printed when Soar is stopped Description The stop soar command stops any running Soar agents It sets a flag in the Soar kernel so that Soar will stop running at a safe point and return control to the user This command is usually not issued at the command line prompt a more common use of this command would be for instance as a side effect of pressing a button on a Graphical User Interface GUI Default Aliases Alias Maps to interrupt stop soar Ss stop
75. S defines the left hand side of the production and specifies the conditions under which the rule can be fired Its syntax is given in detail in a subsequent section The gt symbol serves to separate the LHS and RHS portions The RHS defines the right hand side of the production and specifies the assertions to be made and the actions to be performed when the rule fires The syntax of the allowable right hand side actions are given in a later section Section 3 3 gives an elaborate discussion of the design and coding of productions If the name of the new production is the same as an existing one the old production will be overwritten excised RULE FLAGS The optional FLAGs are given below Note that these switches are preceeded by a colon instead of a dash this is a Soar parser convention O support specifies that all the RHS actions are to be given o support when the production fires no support specifies that all the RHS actions are only to be given i support when the production fires default specifies that this production is a default production this matters for excise task and watch task chunk specifies that this production is a chunk this matters for learn trace interrupt specifies that Soar should stop running when this production matches but before it fires this is a useful debugging tool Multiple flags may be used but not both of o support and no support Although you could force your productions to provide
76. The Soar User s Manual Version 8 6 3 John E Laird and Clare Bates Congdon User interface sections by Karen J Coulter Electrical Engineering and Computer Science Department University of Michigan Draft of October 31 2006 Errors may be reported to John E Laird laird umich edu Copyright 1998 2006 The Regents of the University of Michigan Development of earlier versions of this manual were supported under contract N00014 92 K 2015 from the Advanced Systems Technology Office of the Advanced Research Projects Agency and the Naval Research Laboratory and contract N66001 95 C 6013 from the Advanced Systems Technology Office of the Advanced Research Projects Agency and the Naval Command and Ocean Surveillance Center RDT amp E division Contents Contents v 1 Introduction 11 12 1 3 1 Using this Manual cc ae ie a eased sa toe ew ER ae SB EA 2 Contacting the Sear Group c cr ec necs be KR eee ER EES 3 A Note on Different Platforms and Operating Systems 4 2 The Soar Architecture 21 ae 2 3 2 4 2 5 2 6 2 7 25 5 An Overview of Soar s ew ew REE ERMA eRe ORES 5 2 1 1 Problem Solving Functions in Soar 6 2 1 2 An Example Task The Blocks World 7 2 1 3 Representation of States Operators and Goals 8 2 1 4 Proposing candidate operators 24 9 2 1 5 Comparing candidate operators Preferences 9 2 1 6 Selecting a single operator
77. When a chunk is built all occurrences of the same identifier are replaced with the same variable This can lead to an overspecific chunk when two variables are forced to be the same in the chunk even though distinct variables in the original productions just happened to match the same identifier A chunk s conditions are also constrained by any not equal lt gt tests for pairs of indentifiers used in the conditions of productions that are included in the chunk These tests are saved in the production traces and then added in to the chunk 4 4 Ordering Conditions Since the efficiency of the Rete matcher depends heavily upon the order of a produc tion s conditions the chunking mechanism attempts to write the chunk s conditions in the most favorable order At each stage the condition ordering algorithm tries to determine which eligible condition if placed next will lead to the fewest number of partial instantiations when the chunk is matched A condition that matches an object with a multi valued attribute will lead to multiple partial instantiations so it is generally more efficient to place these conditions later in the ordering This is the same process that internally reorders the conditions in user defined pro ductions as mentioned briefly in Section 2 3 1 4 5 Inhibition of Chunks When a chunk is built it may be able to match immediately with the same working memory elements that participated in its creation If the prod
78. a link into the structure of the input link rather than copy the information The attributes x location and y location are assumed to be values and not identifiers so the same variable names may be used to do the copying A production that creates wmes on the output link for the blocks task might look like this sp blocks world apply move block send output command state lt s gt operator lt o gt io output link lt out gt lt o gt name move block moving block lt bi gt destination lt b2 gt 3 5 SOAR I O INPUT AND OUTPUT IN SOAR 73 lt b1 gt x location lt x1 gt y location lt y1 gt lt b2 gt x location lt x2 gt y location lt y2 gt gt lt out gt move block lt b1 gt x destination lt x2 gt y destination lt y2 gt 1 This production would create substructure on the output link that the output func tion could interpret as being a command to move the block to a new location 74 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS Chapter 4 Learning Chunking is Soar s learning mechanism the sole learning mechanism in Soar Chunk ing creates productions called chunks that summarize the processing required to produce the results of subgoals When a chunk is built it is added to production memory where it will be matched in similar situations avoiding the need for the sub goal Chunks are created only when results are formed in subgoals since most Soar programs are
79. a positive integer Description This command sets and prints the maximum number of elaboration cycles allowed If n is given it must be a positive integer and is used to reset the number of allowed 128 CHAPTER 5 THE SOAR USER INTERFACE elaboration cycles The default value is 100 max elaborations with no arguments prints the current value max elaborations controls the maximum number of elaborations allowed in a single decision cycle The elaboration phase will end after maz elaboration cycles have completed even if there are more productions eligible to fire or retract and Soar will proceed to the next phase after a warning message is printed to notify the user This limits the total number of cycles of parallel production firing but does not limit the total number of productions that can fire during elaboration This limit is included in Soar to prevent getting stuck in infinite loops such as a production that repeatedly fires in one elaboration cycle and retracts in the next if you see the warning message it may be a signal that you have a bug your code However some Soar programs are designed to require a large number of elaboration cycles so rather than a bug you may need to increase the value of maz elaborations In Soar8 maz elaborations is checked during both the Propose Phase and the Apply Phase If Soar8 runs more than the max elaborations limit in either of these phases Soar8 proceeds to the next phase eit
80. an element to working memory 148 alias Define a new command using existing com 151 mands and arguments attribute preferences mode For Soar 7 controls the handling of preferences 121 for non context slots cd Change directory 137 chunk name format Specify format of the name to use for new 107 chunks clog Record all user interface input and output toa 138 file default wme depth Set the level of detail used to print WMEs 93 dirs List the directory stack 140 echo Print a string to the current output device 141 excise Delete Soar productions from production mem 85 ory explain backtraces Print information about chunk and justification 121 backtraces firing counts Print the number of times each production has 108 fired gds print Print the WMEs in the goal dependency set for 95 each goal help Provide formatted on line information about 86 Soar commands indifferent selection Controls indifferent preference arbitration 124 init soar Reinitialize Soar so a program can be rerun from 86 scratch internal symbols Print information about the Soar symbol table 95 learn Set the parameters for chunking Soar s learning 125 mechanism ls List the contents of the current working direc 141 tory matches Print information about the match set and par 96 tial matches max chunks Limit the number of chunks created during a 126 decision cycle max elaborations Limit the maximum number of elaboration cy 127 cles max nil
81. and performing the probabilistic selection details are given in the description of the numeric indifferent mode command on page 131 Require A require preference states that the value must be selected if the goal is to be achieved Prohibit A prohibit preference states that the value cannot be selected if the goal is to be achieved If a value has a prohibit preference it will not be selected for a value of an augmentation independent of the other preferences If there is an acceptable preference for a value of an operator and there are no other competing values that operator will be selected If there are multiple acceptable preferences for the same state but with different values the preferences must be evaluated to determine which candidate is selected If the preferences can be evaluated without conflict the appropriate operator aug mentation of the state will be added to working memory This can happen when they all suggest the same operator or when one operator is preferable to the others that have been suggested When the preferences conflict Soar reaches an impasse as described in Section 2 6 Preferences can be confusing for example there can be two suggested values that are both best which again will lead to an impasse unless additional preferences resolve this conflict or there may be one preference to say that value A is better than value B and a second preference to say that value B is better than value A
82. and the context The following sections describe further how the GDS works and how to use the GDS in behavior systems as well as how the GDS is implemented in the Soar kernel Dependency Set a specific example even though goals have not been an explicit behavior level Soar construct since Soar 6 173 I Supported Feature O Supported Feature Figure E 1 Simplified Representation of the context dependencies above the line local os upported WMEs below the line and the generation of a result In Soar 7 this situation led to non contemporaneous constraints in the chunk that generates 3 Behavior level view of the Goal Dependency Set This section discusses what the GDS does and how that impacts production knowl edge design and implementation Operation of the Goal Dependency Set Whenever a feature is created added to working memory in the Soar 7 architecture that feature will persist for some time The persistence of features may differ with respect to how long the features remain in memory and more importantly what circumstances cause the feature to be removed The Soar 7 architecture utilizes three primary types of persistence i support o support and c support The weakest persistence is instantiation support An isupported feature exists in memory only as long as the production which lead to the feature s creation remains instantiated Thus the WME de
83. antiations 18 CHAPTER 2 THE SOAR ARCHITECTURE of the same production may match at the same time and therefore fire at the same time If blocks A and B are clear the first production without variables will suggest one operator However if a production was created that used variables to test the names this second production will be instantiated twice and therefore suggest two operators one operator to move block A ontop of block B and a second operator to move block B ontop of block A Because the identifiers of objects are determined at runtime literal identifiers cannot appear in productions Since identifiers occur in every working memory element variables must be used to test for identifiers and using the same variables across multiple occurrences is what links conditions together Just as the elements of working memory must be linked to a state in working memory so must the objects referred to in a production s conditions That is one condition must test a state object and all other conditions must test that same state or objects that are linked to that state 2 3 2 Architectural roles of productions Soar productions can fulfill four different roles the three knowledge retrieval problem solving functions and the state elaboration function all described on page 6 Operator proposal Operator comparison Operator selection is not an act of knowledge retrieval Operator application State elaboration or WN
84. ar and a robotic arm executing command outputs The camera image might be analyzed by a separate vision program this 70 red blue day 7 TOO OY a CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS x location yellow Figure 3 3 An example portion of the input link for the blocks world task program could have as its output the locations of blocks on an xy plane The Soar input function could take the output from the vision program and create the following working memory elements on the input link all identifiers are assigned at runtime this is just an example of possible bindings S1 io I1 I1 input link I2 I2 block B1 I2 block B2 I2 block B3 B1 x location 1 B1 y location 0 B1 color red B2 x location 2 B2 y location 0 B2 color blue B3 x location 3 B3 y location 0 B3 color yellow A A The A notation in the example is used to indicate the working memory elements that are created by the architecture and not by the input function This configuration of blocks corresponds to all blocks on the table as illustrated in the initial state in Figure 2 2 3 5 SOAR I O INPUT AND OUTPUT IN SOAR 71 moving block yellow mc gt Figure 3 4 An example portion of the output link for the blocks world task Then during the Apply Phase of the execution cycle Soar productions could respond to an operato
85. ases Alias Maps to rn rete net See Also excise init soar 5 5 11 set library location Set the top level directory containing demos help ete Synopsis set library location directory Options directory The new desired library location Description Invoke with no arguments to query what the current library location is The library location should contain at least the help subdirectory and the command names file for help to work See Also help 5 5 12 source Load and evaluate the contents of a file 146 CHAPTER 5 THE SOAR USER INTERFACE Synopsis source adv filename Options filename The file of Soar productions and commands to load a all Enable a summary for each file sourced d disable Disable all summaries v verbose Print excised production names Description Load and evaluate the contents of a file The filename can be a relative path or a fully qualified path source will generate an implicit push to the new directory execute the command and then pop back to the current working directory from which the command was issued After the source completes the number of productions sourced and excised is printed agent gt source demos mac mac soar ER kkk k Total 18 productions sourced Source finished agent gt source demos mac mac soar HK HEK HE AHR EERE HK HK HEK KEE AH AH HE H Total 18 productions sourced
86. atches command can be used to print information about partial matches for a named production In this case the conditions of the production are listed each preceded by the number of currently active matches for that condition If a condition is negated it is preceded by a 98 CHAPTER 5 THE SOAR USER INTERFACE minus sign The pointer gt gt gt gt before a condition indicates that this is the first condition that failed to match When printing partial matches the default action is to print only the counts of the number of WME s that match and is a handy tool for determining which condition failed to match for a production that you thought should have fired At levels timetags and wmes the matches command displays the WME s immediately after the first condition that failed to match temporarily interrupting the printing of the production conditions themselves Notes When printing partial match information some of the matches displayed by this command may have already fired depending on when in the execution cycle this command is called To check for the matches that are about to fire use the matches command without a named production In Soar 8 the execution cycle decision cycle is input propose decide apply output it no longer stops for user input after the decision phase when running by decision cycles run d 1 If a user wishes to print the match set immediately after the decision phase and before the apply phase
87. atgh wmes o deh ae eA eA SS a 118 5 4 Configuring Soar s Runtime Parameters 0 120 5 4 1 attribute preferences mode 121 5 4 2 explain backtraces 121 5 4 3 indifferent selection 124 DAA DEG o oe 6 6 cere kae RG OE Ow Oe ata RS 125 DAD TUAHCHUNKS sso ranea re Oe a ee we BE 126 5 4 6 max elaborations 050 0000 127 5 4 7 max memory usage 04 128 5 4 8 max nil output cycles 129 549 multi attributes gt o os 54 4644 seb Ee GH 130 5 4 10 numeric indifferent mode 131 5 4 11 omsupport mode 0 2 00408 132 5 4 12 save backtraces 0 4 132 5 4 13 set stop phase 2 2 0000 133 Dat SOP 64 4 wick wa ee ha we a ee eR eA OED 134 DA SAMOS acao ra ee ae eR eh he A we a eo eS 135 DAG WARES ck wc ce we eroaa eR ee eRe eS 136 5 5 File System I O Commands 200 558 ec eae 136 DiE Ea o ge a ee ee a ee y ew ws a 137 Ore glog on od a acti pe oe be aw a Kae ge ee YR A 138 5 5 3 cGommand to file 550008 139 ieee GIRS og eae oe Se Oi ew we a Haw oar ee ee 140 ie GUI he ans g aie ow etek ee ee pS 141 Oe AB ea eS ke a cae Hh AE e a i a 141 Se POPI cuero i Eae Ee a ae OS aa 142 DOO PUSKA sa 6 62 Re e EG a Om a oe EOS 143 DoD PEI eeina an E Be ek SE A a Sod Be Hoe Be ose 143 5 5 10 rete net 0 es 144 lv 5 0 11 set library location
88. block and the bottom block HH HH HOH H OH OH sp blocks world apply move block add new ontop state lt s gt operator lt o gt 161 lt o gt name move block moving block lt block1 gt destination lt block2 gt gt lt s gt ontop lt ontop gt lt ontop gt top block lt block1 gt bottom block lt block2 gt HEHHHHEHHHHEHRHHAARHHEAREAEE REAR RARER AERA ERR R ER AH RHR R EERE R RRR R RRA HEHHHHEHHHHEHEAHEAREHEAREHEAAE AERA EERE A AERA ERR AR EERE R RHR AR PREAH RRA Detect that the goal has been achieved HH HH HH H OH OF The conditions establish that 1 The state has a problem space named blocks 2 The state has three ontop relations a a block named A is ontop a block named B b a block named B is ontop a block named C c a block named C is ontop a block named TABLE The actions 1 print a message for the user that the A B C tower has been built 2 halt Soar sp blocks world detect goal state lt s gt problem space blocks ontop lt AB gt lt gt lt gt lt AB gt top block lt BC gt top block lt CT gt top block lt A gt lt B gt lt C gt lt T gt gt write crlf type type type type halt block block block table lt AB gt lt BC gt lt AB gt lt gt lt BC gt lt CT gt lt A gt bottom block lt B gt lt B gt bottom block lt C gt lt C gt botto
89. blocks A B and C on the table This is the first production that will fire Soar creates the initial state as an architectural function in the zeroth decision cycle which will match against this production This production does a lot of work because it is creating preferences for all the structure for the initial state 1 The state has a problem space named blocks The problem space limits the operators that will be selected for a task In this simple problem it isn t really necessary there is only one operator but it s a programming convention that you should get used to 2 The state has four things three blocks and the table The state has three ontop relations 4 Each of the things has substructure their type and their names Note that the fourth thing is actually a table 5 Each of the ontop relations has substructure the top thing and the bottom thing Finally the production writes a message for the user HH HH HH HH HH HH FH OH OH OF w 157 158 APPENDIX A THE BLOCKS WORLD PROGRAM Note that this production will fire exactly once and will never retract sp blocks world elaborate initial state state lt s gt superstate nil ie lt s gt problem space blocks thing lt block A gt lt block B gt lt block C gt lt table gt ontop lt ontop A gt lt ontop B gt lt ontop C gt lt block A gt type block name A lt block B gt ty
90. borations Operator elaborations i e placing some information on an operator WME should be i supported when using Soar 8 since this information is by definition temporary not persistent because it s located on the non persistent operator However the kernel itself hasn t kept up with this change Prior to Soar 8 5 Soar s o support modes computed operator elaborations as o supported resulting in the context conditions being added to the GDS This often leads to unwanted unnecessary retractions If you are using a version prior to Soar 8 you should declare any operator elaborations i supported i e using i support Kernel level view of the Goal Dependency Set The actual implementation of the GDS in the Soar kernel is slightly more complex than the conceptual description of the previous section but not significantly so Elements are added the GDS via elaborate_gds a procedure in decide c that mimics the chunking backtrace function The algorithm is shown in Figure E 3 When an o supported preference is asserted elaborate_gds is called Conditions in a production instantiation that are located in a higher context can be added directly to the GDS 1 For local conditions elaborate_gds first checks whether the tested WME is o supported or if it has been previously been back traced through 2 If either of these are true the WME can be ignored because it s dependencies have been added to the GDS previously If no
91. ce sufficient knowledge has been retrieved This is performed by Soar s decision proce dure which is a fixed procedure that interprets preferences that have been created by the retrieval functions The knowledge retrieval and decision making functions combine to form Soar s decision cycle When the knowledge to perform the problem solving functions is not directly available in productions Soar is unable to make progress and reaches an impasse There are three types of possible impasses in Soar 1 An operator cannot be selected because none are proposed 2 An operator cannot be selected because multiple operators are proposed and the comparisons are insufficient to determine which one should be selected 3 An operator has been selected but there is insufficient knowledge to apply it In response to an impasse the Soar architecture creates a substate in which operators can be selected and applied to generate or deliberately retrieve the knowledge that was not directly available the goal in the substate is to resolve the impasse For example in a substate a Soar program may do a lookahead search to compare candidate operators if comparison knowledge is not directly available Impasses and substates are described in more detail in Section 2 6 2 1 2 An Example Task The Blocks World We will use a task called the blocks world as an example throughout this manual In the blocks world task the initial state has three blocks named A
92. ced Soar users for example those who need to write their own parsers B 1 Grammar of Soar productions A grammar for Soar productions is lt soar production gt sp lt production name gt lt documentation gt lt flags gt lt condition side gt gt lt action side gt lt documentation gt se lt string gt lt flags gt o support i support chunk default B 1 1 Grammar for Condition Side Below is a grammar for the condition sides of productions lt condition side gt lt state imp cond gt lt cond gt lt state imp cond gt state impasse lt id_test gt lt attr_value_tests gt lt cond gt lt positive_cond gt lt positive_cond gt lt positive_cond gt lt conds_for_one_id gt lt cond gt lt conds_for_one_id gt state impasse lt id_test gt lt attr_value_tests gt lt id_test gt lt test gt 163 164 lt attr_value_tests gt lt attr_test gt lt value_test gt lt test gt lt conjunctive_test gt lt simple_test gt lt disjunction_test gt lt relational_test gt lt relation gt lt single_test gt lt variable gt lt constant gt APPENDIX B GRAMMARS FOR PRODUCTION SYNTAX lt attr_test gt lt attr_test gt lt value_test gt lt test gt lt test gt lt conds_for_one_id gt lt conjunctive_test gt lt simple_test gt lt simple_tes
93. ch command allows users to monitor when chunks and justifications are created by specifying one of the following arguments to the watch learning command Argument Alias Effect noprint 0 Print nothing about new chunks or justifica tions default print 1 Print the names of new chunks and justifica tions when created fullprint 2 Print entire chunks and justifications when created Watching other Functions Option Flag Argument Description to Option b backtracing remove Controls the printing of backtracing in optional formation when a chunk or justification is created i indifferent selection remove Controls the printing of the scores for optional tied operators in random indifferent se lection mode Description The watch command controls the amount of information that is printed out as Soar runs The basic functionality of this command is to trace various levels of information about Soar s internal workings The higher the level the more information is printed as Soar runs At the lowest setting 0 none nothing is printed The levels are cumulative so that each successive level prints the information from the previous level as well as some additional information The default setting for the watch level is 1 or decisions Each level can be indicated with either a number or a series of flags as follows O or none 1 or decisions 2 or
94. ch newly counted item replaces the old value of the count 3 Remembering Agents oftentimes need to remember an external situation or stimulus even when that perception is no longer available 4 Avoiding Expensive Computations In some situations an agent may have the information needed to assert some belief in a new world state but the expense of performing the computation necessary for the assertion given what is already known makes the computation avoidable For example in dynamic complex domains determining when to make an expensive calculation is often formulated as an explicit agent task When remembering or avoiding an expensive computation the agent designer is mak ing a commitment to retain something even though it might not be supported in the current context In Soar 8 these WMEs should be asserted in the top state For many Soar systems especially those focused on execution in a dynamic environment most o supported elements will need to be stored on the top state 177 For any kind of local non monotonic reasoning about the context counting projec tion planning features should be stored locally When a dependent context change occurs the GDS interrupts the processing by removing the state While this may seem like a severe over reaction formal and empirical analysis have suggested that this solution is less computationally expensive than attempting to identify the specific dependent assumption Operator Ela
95. chapter describe the memories and processes of Soar working memory production memory preference memory Soar s execution cycle the decision procedure learning and how input and output fit in 2 2 Working memory The Current Situation Soar represents the current problem solving situation in its working memory Thus working memory holds the current state and operator and is Soar s short term knowledge reflecting the current knowledge of the world and the status in problem solving Working memory contains elements called working memory elements or WME s for short Each WME contains a very specific piece of information for example a WME might say that B1 is a block Several WME s collectively may provide more infor mation about the same object for example B1 is a block B1 is named A Bl is on the table etc These WME s are related because they are all contributing to the description of something that is internally known to Soar as B1 B1 is called an identifier the group of WME s that share this identifier are referred to as an object in working memory Each WME describes a different attribute of the object for example its name or type or location each attribute has a value associated with it for example the name is A the type is block and the position is on the table Therefore each WME is an identifier attribute value triple and all WME s with the same identifier are part of th
96. ciency This command is used only to provide hints to the production condition reorderer so it can produce better condition orderings Better orderings enable the rete network to run faster This command has no effect on the actual contents of working memory and most users needn t use this at all Note that multi attributes declarations must be made before productions are loaded into soar or this command will have no effect Examples Declare the symbol thing to be an attribute likely to take more than 1 but no more than 4 values multi attributes thing 4 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 131 5 4 10 numeric indifferent mode Select method for combining numeric preferences Synopsis numeric indifferent mode as Options a avg average Use average mode default s sum Use sum mode Description The numeric indifferent mode command is used to select the method for combining numeric preferences This command is only meaningful in indifferent selection random mode The default procedure is avg average which assigns a final value to an operator according to the rule e If the operator has at least one numeric preference assign it the value that is the average of all of its numeric preferences e If the operator has no numeric preferences but has been included in the indif ferent selection through some combination of non numeric preferences assign it the value 50
97. continuously subgoaling and returning results to higher level states chunks are typically created continuously as Soar runs This chapter begins with a discussion of when chunks are built Section 4 1 below followed by a detailed discussion of how Soar determines a chunk s conditions and actions Section 4 2 Sections 4 3 through 4 4 examine the construction of chunks in further detail Section 4 5 explains how and why chunks are prevented from match ing with the WME s that led to their creation Section 4 6 reviews the problem of overgeneral chunks 4 1 Chunk Creation Several factors govern when chunks are built Soar chunks the results of every subgoal unless one of the following conditions is true 1 Learning is off See Section 5 4 4 on page 125 for details of learn used to turn learning off Learning can be set to on or off When learn is on chunks are built When learn is off chunks are not built 2 Learning is set to bottom up and a chunk has already been built for a subgoal of the state that generated the results See Section 5 4 4 on page 125 for details of learn used to set learning to bottom up With bottom up learning chunks are learned only in states in which no subgoal has yet generated a chunk In this mode chunks are learned only for the bot 75 76 CHAPTER 4 LEARNING tom of the subgoal hierarchy and not the intermediate levels With experience the subgoals at the bottom will be replaced by t
98. ctedly often something has changed in the goal dependency set causing a subgoal to be regenerated prior to producing a result Warnings gds print is horribly inefficient and should not generally be used except when some thing is going wrong and you need to examine the Goal Dependency Set Default Aliases Alias Maps to gds_ print gds print 5 2 3 internal symbols Print information about the Soar symbol table Synopsis internal symbols 96 CHAPTER 5 THE SOAR USER INTERFACE Options No options Description The internal symbols command prints information about the Soar symbol table Such information is typically only useful for users attempting to debug Soar by lo cating memory leaks or examining I O structure Example soar gt internal symbols Symbolic Constants operator accept evaluate object problem space sqrt interrupt mod goal io additional symbols deleted for brevity Integer Constants Floating Point Constants Identifiers Variables lt o gt lt sso gt lt to gt lt ss gt lt ts gt lt so gt lt sss gt 5 2 4 matches Prints information about partial matches and the match set 5 2 EXAMINING MEMORY 97 Synopsis matches nctw production_name matches alr nctw Options production_name Print partial match information for the named produc tion n names c count For
99. ction actions 18 production memory 16 syntax 38 production find 105 prohibit preference 78 80 168 pushd 143 pwatch 109 pwd 143 quiescence 22 quiescence t augmentation 67 76 81 quit 87 refractory inhibition of chunks 79 reject preference 168 remove wme 149 require preference 78 80 167 result 22 27 75 77 rete net 144 RHS of production 56 run 88 save backtraces 132 set library location 145 set stop phase 133 soar8 134 soarnews 154 source 145 sp 90 srand 153 stack see goal state 16 representation 8 184 state no change impasse 25 stats 110 stop soar 92 structured value notation 55 subgoal 25 see goal 66 75 augmentations 67 result 76 termination 67 subgoal result 77 superstate 67 support 165 symbol 34 symbolic constant 34 tie impasse 24 67 time 154 timers 135 timestamp 63 timetag 35 top state for I O 72 trace memory 77 type comparisons 43 unalias 155 Unix 4 value 14 33 34 structured notation 55 variable 164 action side 57 variables 42 variablization 79 verbose 112 version 156 waitsnc 136 warnings 113 watch 113 watch wmes 118 Windows 4 WME see working memory element working memory 14 14 acceptable preference 36 object 14 size 111 syntax 33 trace 77 working memory element 14 INDEX syntax 33 timetag see timetag worse preference 168 worst preference 169 write 60 INDEX
100. ctness 80 4 6 2 Testing for local negated conditions 80 4 6 3 Testing for the substate A we hee Be Sew ee we 81 5 The Soar User Interface 83 5 1 Basic Commands for Running Soar gt ss ss se bse ew Oe de eS 84 SLI ECIS ocu eoa kw eee Kaiki aara aa anaa AES 85 DL Helpe oi re eae ee ES AER AD ee h 86 513 nit soaf 4 14 24 ra mau yaaa de ERS ER SG 86 A a E a e aa es a a Ee Oe te es 87 SLD BUR oe e bana HE HOS w ae deai e PEGS ay io aa iG 88 PE 1 ee Gata eae ee a ee ee es ee es 90 SLC MWEOD S0RE s 5 44 4 4b 4G AE AE a a RE ARS RE HS 92 CONTENTS iii 5 2 Examining Memory s sss ae Emea BES kir a Eo kde Pos eS 93 5 2 1 default wme depth 93 Se gapin le roe a EA Rd Oe Sod Be Boe Bw eds 95 5 2 3 internal symbols 2 426 vB ee crede cades 95 D24 MASON oeo irona r Ew OE SE ede e ai DER ea 96 5 2 5 memories 2 224 4s de aaa ESE HE ED REO EE 98 5 2 6 preferences 2 ee kde bee DEEDS RE ES GO 99 527 WHINE oo 54 bb 65h RAG SAGES EA REGS BED SH 102 S20 production find i eset cee eo goe soma eR a 105 5 3 Configuring Trace Information and Debugging 106 5 3 1 chunk name format 107 Wie Gee INORHCOUNTE 2 2 54 ho 4 ee HE g eA ee He DES 108 ee IMC e a SS be FS ee A ee ee ee N 109 We SEAS stan che ae chew eee ee ee pe de eS 110 5 3 5 verbose 1 ee 112 520 Warnings pe eS OAS eR Ree REE Se SE SED 113 Gal WHO eeo gond ee ae aw we a ew a Be Be 113 yy W
101. curs a production can test for the resulting substate and create a result for the original subgoal This form of state test builds overgeneral chunks because no pre existing structure is relevant to the result that terminates the subgoal The result is dependent only on the existence of the substate within a substate Solution The current solution to this problem is to allow the problem solving to signal the architecture that the test for a substate is being made The signal used by Soar is a test for the quiescence t augmentation of the subgoal The chunking mechanism recognizes this test and does not build a chunk when it is found in a backtrace of a subgoal The history of this test is maintained so that if the result of the substate is then used to produce further results for a superstate no higher chunks will be built However if the result is used as search control it is a desirability preference then it does not prevent the creation of chunks because the original result is not included in the backtrace If the quiescence t being tested is connected to a superstate it will not inhibit chunking and it will be included in the conditions of the chunk 82 CHAPTER 4 LEARNING Chapter 5 The Soar User Interface This chapter describes the set of user interface commands for Soar All commands and examples are presented as if they are being entered at the Soar command prompt This chapter is organized into 7 sections 1 Basic
102. cution select apply select apply select apply Figure 2 1 Soar is continually trying to select and apply operators working memory can be thought of as the program for Soar The Soar architecture cannot solve any problems without the addition of long term knowledge Note the distinction between the Soar architecture and the Soar program The former refers to the system described in this manual common to all users and the latter refers to knowledge added to the architecture A Soar program contains the knowledge to be used for solving a specific task or set of tasks including information about how to select and apply operators to transform the states of the problem and a means of recognizing that the goal has been achieved 2 1 1 Problem Solving Functions in Soar All of Soar s long term knowledge is organized around the functions of operator selec tion and operator application which are organized into four distinct types of knowl edge Knowledge to select an operator 1 Operator Proposal Knowledge that an operator is appropriate for the current situation 2 Operator Comparison Knowledge to compare candidate operators 3 Operator Selection Knowledge to select a single operator based on the comparisons Knowledge to apply an operator 4 Operator Application Knowledge of how a specific operator modifies the state In addition there is a fifth type of knowledge in Soar that is indirectly connecte
103. d by gt In the examples in this manual we use soar gt e Comments in the examples are preceded by a and in line comments are preceded by For many commands there is some flexibility in the order in which the arguments may be given See the online help for each command for more information We have not incorporated this flexible ordering into the syntax specified for each command because doing so complicates the specification of the command When the order of arguments will affect the output produced by a command the reader will be alerted 5 1 Basic Commands for Running Soar This section describes the commands used to start run and stop a Soar program to invoke on line help information and to create and delete Soar productions The specific commands described in this section are Summary excise Delete Soar productions from production memory help Provide formatted on line information about Soar commands init soar Reinitialize Soar so a program can be rerun from scratch quit Close log file terminate Soar and return user to the operating system run Begin Soar s execution cycle cd sp Create a production and add it to production memory stop soar Interrupt a running Soar program These commands are all frequently used anytime Soar is run 5 1 BASIC COMMANDS FOR RUNNING SOAR 85 5 1 1 excise Delete Soar productions from production memory Synopsis excise product
104. d from the time a decision cycle or number of decision cycles is initiated until stopped Kernel time is the time spent in core Soar functions In this case kernel time is defined as the all functions other than the execution of callbacks and the input and output functions The total kernel timer is only stopped for these functions The phase timers for the kernel and callbacks track the execution time for individual phases of the decision cycle i e input phase preference phase working memory phase output phase and decision phase Because there is overhead associated with turning these timers on and off the actual kernel time will always be greater than the derived kernel time i e the sum of all the phase kernel timers Similarly the total CPU time will always be greater than the derived total the sum of the other timers because the overhead of turning these timers on and off is included in the total CPU time In general the times reported by the single timers should always be greater than than the corresponding derived time Additionally as execution time increases the difference between these two values will also increase For those concerned about the performance cost of the timers all the run time timing calculations can be compiled out of the code by defining NO TIMING STUFF in soarkernel h before compilation 5 3 5 verbose Control detailed information printed as Soar runs Synopsis verbose ed Options d
105. d to both operator selection and operator application 5 Knowledge of monotonic inferences that can be made about the state state elaboration 2 1 AN OVERVIEW OF SOAR T State elaborations indirectly affect operator selection and application by creating new descriptions of the current situation that can cue the selection and application of operators These problem solving functions are the primitives for generating behavior in Soar Four of the functions require retrieving long term knowledge that is relevant to the current situation elaborating the state proposing candidate operators comparing the candidates and applying the operator by modifying the state These functions are driven by the knowledge encoded in a Soar program Soar represents that knowledge as production rules Production rules are similar to if then statements in conven tional programming languages For example a production might say something like f there are two blocks on the table then suggest an operator to move one block ontop of the other block The if part of the production is called its conditions and the then part of the production is called its actions When the conditions are met in the current situation as defined by working memory the production is matched and it will fire which means that its actions are executed making changes to working memory The other function selecting the current operator involves making a decision on
106. d to a named production u user print the names of all user productions currently loaded production name print the production named production name Printing items in working memory d depth n This option overrides the default printing depth see the default wme depth command for more detail i internal items should be printed in their internal form For working memory this means printing the individual elements with their timetags rather than the objects v varprint Print identifiers enclosed in angle brackets identifier print the object identifier identifier must be a valid Soar symbol such as S1 pattern print the object whose working memory elements matching the given pattern See Description for more information on printing objects matching a specific pattern timetag print the object in working memory with the given timetag 104 CHAPTER 5 THE SOAR USER INTERFACE Printing the current subgoal stack s stack Specifies that the Soar goal stack should be printed By default this includes both states and operators o operators When printing the stack print only operators S states When printing the stack print only states Description The print command is used to print items from production memory or working memory It can take several kinds of arguments When printing items from working memory the Soar objects are printed unless t
107. ded at the end of the file 5 5 FILE SYSTEM I O COMMANDS 139 Description The clog command allows users to save all user interface input and output to a file When Soar is logging to a file everything typed by the user and everything printed by Soar is written to the file in addition to the screen Invoke clog with no arguments or with q to query the current logging status Pass a filename to start logging to that file relative to the command line interface s home directory Use the close option to stop logging Examples To initiate logging and place the record in foo log clog foo log To append log data to an existing foo log file clog A foo log To terminate logging and close the open log file clog c See Also command to file Known Issues Does not log everything when structured output is selected 5 5 3 command to file Dump the printed output and results of a command to a file Synopsis command to file a filename command args 140 CHAPTER 5 THE SOAR USER INTERFACE Options a append Append if file exists filename The file to log the results of the command to command The command to log args Arguments for command Description This command logs a single command It is almost equivalent to opening a log using clog running the command then closing the log the only difference is that input isn t recorded Running this command while a log is open
108. destination lt d1 gt lt o2 gt name move block moving block lt m2 gt lt gt lt m1 gt destination lt d2 gt gt 3 3 5 10 Attribute tests The previous examples applied all of the different test to the values of working memory elements All of the tests that can be used for values can also be used for attributes and identifiers except those including constants Variables in attributes Variables may be used with attributes as in sp blocks example production conditions state lt s gt operator lt o gt thing lt t gt lt gt lt t gt lt t2 gt operator lt o gt name group py attribute lt a gt moving block lt t gt destination lt t2 gt lt t gt type block lt a gt lt x gt lt t2 gt type block lt a gt lt x gt gt lt s gt operator lt o gt gt 50 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS This production tests that there is acceptable operator that is trying to group blocks according to some attribute lt a gt and that block lt t gt and lt t2 gt both have this at tribute whatever it is and have the same value for the attribute Predicates in attributes Predicates may be used with attributes as in sp blocks example production conditions state operator lt o gt table lt t gt lt t gt lt gt type table gt F which tests that the object with its identifier bound to lt t gt must have an attribut
109. ding to the tokens that are allocated in the rete network for the given production s This number is a function of the number of elements in working memory that match each production Therefore this command will not provide useful information at the beginning of a Soar run when working memory is empty and should be called in the middle or at the end of a Soar run The memories command is used to find the productions that are using the most memory and therefore may be taking the longest time to match this is only a heuristic By identifying these productions you may be able to rewrite your program so that it will run more quickly Note that memory usage is just a heuristic measure of the match time A production might not use much memory relative to others but may still be time consuming to match and excising a production that uses a large number of tokens may not speed up your program because the Rete matcher shares common structure among different productions As a rule of thumb numbers less than 100 mean that the production is using a small amount of memory numbers above 1000 mean that the production is using a large amount of memory and numbers above 10 000 mean that the production is using a very large amount of memory See Also matches 5 2 6 preferences Examine details about the preferences that support the specified id and attribute 100 CHAPTER 5 THE SOAR USER INTERFACE Synopsis preferences 0123nNtwo id attr
110. e whose value is table but the name of this attribute is not type Disjunctions of attributes Disjunctions may also be used with attributes as in sp blocks example production conditions state operator lt o gt table lt t gt lt t gt lt lt type name gt gt table gt T which tests that the object with its identifier bound to lt t gt must have either an attribute type whose value is table or an attribute name whose value is table Conjunctive tests for attributes Section 3 3 5 5 illustrated the use of conjunctions for the values in conditions Con junctive tests may also be used with attributes as in sp blocks example production conditions state operator lt o gt table lt t gt lt t gt lt ta gt lt gt name table gt oe which tests that the object with its identifier bound to lt t gt must have an attribute whose value is table and the name of this attribute is not name and the name of this attribute whatever it is is bound to the variable lt ta gt 3 3 PRODUCTION MEMORY 51 When attribute predicates or attribute disjunctions are used with multi valued at tributes the production is rewritten internally to use a conjunctive test for the at tribute the conjunctive test includes a variable used to bind to the attribute name Thus lt p1 gt type father lt gt name sue sally is interpreted to mean lt p1 gt type father lt gt name
111. e Memory 0000 tee ee es 38 oo Produchon Memory c pa eG w eee eee ER Ee Re CHS 38 331 Production Names lt gt 2 60264 24444044 648 242205 40 3 3 2 Documentation string optional a eoa aa 40 3 3 3 Production type optional aa aea a 40 3 3 4 Comments optional ooa a a ewe EDs 41 3 3 5 The condition side of productions or LHS 41 3 3 6 The action side of productions or RHS 56 3 4 Impasses in Working Memory and in Productions 66 3 4 1 Impasses in working memory a saoao 66 3 4 2 Testing for impasses in productions 68 oo Soar 1 O Input and Output in Boar ses seso ar fa 68 Sol Oyerview or Seared c aa day E Ye ew eS 69 3 5 2 Input and output in working memory 69 3 5 3 Input and output in production memory ss wes sersa 72 4 Learning 75 At Chunk CeO e ke ek ee eo SEP eee BUR p eR ee OS 75 4 2 Determining Conditions and Actions 04 76 4 2 1 Determining a chunk s actions 2 6 44 68 542 eos TT 4 2 2 Tracing the creation and reference of working memory elements 77 4 2 3 Determining a chunk s conditions 78 4 3 Variablizing Identifiers i222 idee be ee hwy eee 79 AA Ordering Conditions lt s lt lt sos saoo soas o ke we ew 79 45 Inhibition of Chunks a sa ee ee ee eee e aione emi 79 4 6 Problems that May Arise with Chunking 80 4 6 1 Using search control to determine corre
112. e nil it is as if the user had typed this command 152 CHAPTER 5 THE SOAR USER INTERFACE print i superstate nil To check what a specific alias is defined as you would type alias wmes Default Aliases Alias Maps to a alias See Also unalias 5 7 2 edit production Move focus in an editor to this production Synopsis edit production production_name Options production_name The name of the production to edit Description If an editor currently limited to Visual Soar is open and connected to Soar this command causes the editor to open the file containing this production and move the cursor to the start of the production If there is no editor connected to Soar the command does nothing In order to connect Visual Soar to Soar launch Visual Soar and choose Connect from the Soar Runtime menu Then open the Visual Soar project that you re working on At that point you re set up and edit production will start to work Examples edit production my production name 5 7 MISCELLANEOUS See Also sp 5 7 3 input period For Soar7 mode controls the rate of input to the Soar agent Synopsis input period period Options period A non negative integer Description 153 This command is obsolete for Soar8 In Soar8 input is done at the start of every decision cycle For Soar7 mode the input period command controls the rate of input to
113. e operator 07 This state corresponds to the illustration of working memory in Figure 2 4 3 1 WORKING MEMORY 37 isa Color size apple red small box orange large isa size E identifiers ball red bi mame attributes state values Figure 3 1 A semantic net illustration of four objects in working memory 3 1 5 Working Memory as a Graph Not only is working memory a set it is also a graph structure where the identifiers are nodes attributes are links and constants are terminal nodes Working memory is not an arbitrary graph but a graph rooted in the states Therefore all WMEs are linked either directly or indirectly to a state The impact of this constraint is that all WMEs created by actions are linked to WMEs tested in the conditions The link is one way from the identifier to the value Less commonly the attribute of a WME may be an identifier Figure 3 1 illustrates four objects in working memory the object with identifier X44 has been linked to the object with identifier 043 using the attribute as the link rather than the value The objects in working memory illustrated by this figure are 043 isa apple color red inside 053 size small X44 200 087 isa ball color red inside 053 size big 053 isa box size large color orange contains 043 087 X44 unit grams property mass In this example object 043 and object 087 are both linked to object 053 through 053
114. e same object Objects in working memory are linked to other objects The value of one WME may be an identifier of another object For example a WME might say that B1 is ontop of T1 and another collection of WME s might describe the object T1 T1 is a table T1 is brown and T1 is ontop of F1 And still another collection of WME s might describe the object F1 F1 is a floor etc All objects in working memory must be linked to a state either directly or indirectly through other objects Objects that are not linked to a state will be automatically removed from working memory by the Soar architecture WME s are also often called augmentations because they augment the object pro viding more detail about it While these two terms are somewhat redundant WME is a term that is used more often to refer to the contents of working memory while augmentation is a term that is used more often to refer to the description of an object Working memory is illustrated at an abstract level in Figure 2 3 on page 9 2 2 WORKING MEMORY THE CURRENT SITUATION 15 The attribute of an augmentation is usually a constant such as name or type because in a sense the attribute is just a label used to distinguish one link in working memory from another The value of an augmentation may be either a constant such as red or an identifier such as 06 When the value is an identifier it refers to an object in working memory
115. e the current Rete net or restore a previous one Synopsis rete net s l filename Options s save Save the Rete net in the named file Cannot be saved when there are justifications present Use excise j l r load restore Load the named file into the Rete network work ing memory and production memory must both be empty Use excise a filename The name of the file to save or load Description The rete net command saves the current Rete net to a file or restores a Rete net previously saved The Rete net is Soar s internal representation of production and working memory the conditions of productions are reordered and common substruc tures are shared across different productions This command provides a fast method of saving and loading productions since a special format is used and no parsing is necessary Rete net files are portable across platforms that support Soar Normally users wish to save only production memory Note that justifications cannot be present when saving the Rete net Issuing an init soar before saving a Rete net will remove all justifications and working memory elements If the filename contains a suffix of Z then the file is compressed automatically when it is saved and uncompressed when it is loaded Compressed files may not be 5 5 FILE SYSTEM I O COMMANDS 145 portable to another platform if that platform does not support the same uncompress utility Default Ali
116. ed by numbers which is the format of identifiers The convention for naming productions is to separate important elements with aster isks the important elements that tend to appear in the name are 1 The name of the task or goal e g blocks world 2 The name of the architectural function e g propose 3 The name of the operator or other object at issue e g move block 4 Any other relevant details This name convention enables one to have a good idea of the function of a production just by examining its name This can help for example when you are watching Soar run and looking at the specific productions that are firing and retracting Since Soar uses white space to delimit components of a production if whitespace inadvertently occurs in the production name Soar will complain that an open parenthesis was expected to start the first condition 3 3 2 Documentation string optional A production may contain an optional documentation string The syntax for a docu mentation string is that it is enclosed in double quotes and appears after the name of the production and before the first condition and may carry over to multiple lines The documentation string allows the inclusion of internal documentation about the production it will be printed out when the production is printed using the print command 3 3 3 Production type optional A production may also include an optional production type which may specify that the
117. eed to be specified with a symbol lt s gt operator lt op1 gt is assumed to mean lt s gt operator lt op1 gt Ambiguity can easily arise when using a preference that can be either binary or unary gt lt The default assumption is that if a value follows the preference then the preference is binary It will be unary if a carat up arrow a closing parenthesis another preference or a comma follows it Below are four examples of legal although unrealistic actions that have the same effect lt s gt operator lt 01 gt lt 02 gt lt 02 gt lt lt 01 gt lt 03 gt lt 04 gt lt s gt operator lt 01 gt lt 02 gt lt 02 gt lt lt 01 gt lt 03 gt lt 04 gt lt s gt operator lt ol gt lt 02 gt lt 02 gt lt lt 01 gt lt 04 gt lt 03 gt lt s gt operator lt 01 gt operator lt 02 gt operator lt 02 gt lt lt ol gt operator lt 04 gt lt 03 gt Any one of those actions could be expanded to the following list of preferences lt s gt operator lt ol gt lt s gt operator lt o2 gt lt s gt operator lt 02 gt lt lt 01 gt lt s gt operator lt 03 gt lt s gt operator lt 04 gt Note that structured value notation may not be used in the actions of productions 3 3 6 6 Righthand side Functions The fourth type of action that can occur in productions is called a righthand side function Righthand side
118. ent operator Figure 2 4 illustrates working memory after the first operator has been selected There are six operators proposed and only one of these is actually selected Goals are either represented explicitly as substructure of the state with general rules that recognize when the goal is achieved or are implicitly represented in the Soar program by goal specific rules that test the state for specific features and recognize when the goal is achieved The point is that sometimes a description of the goal will be available in the state for focusing the problem solving whereas other times it may 2 1 AN OVERVIEW OF SOAR 9 B2 B3 B2 is a block B3 is a block B2 is named B B3 is named C B1 B2 is clear B3 is clear B1 is a block B1 is named A i Ti i B1 is clear T1 is a table i S1 l T1 is named table f s i T1 is clear S1 is a state S1 has a problem space blocks O1 h s a top block Bi S1 has a thing B1 01 S1 has a thing B2 1m ae S1 has a thing B3 O1 has i bottom bloc S1 has a thing T1 O2 O2 has a top block B2 S1 has an ontop O1 S1 has an ontop O2 S1 has an ontop O3 03 O3 has a top block B3 k S1 has no operator O3 has a bottom block T1 O2 has a boitom block T1 An Abstract View of Working Memory Figure 2 3 An abstract illustration of the initial state of the blocks world as w
119. er or zero a no change impasse Each step in Figure D 1 is described below RequireTest This test checks for required candidates in preference memory and also constraint failure impasses involving require preferences see Section 2 6 on page 22 e If there is exactly one candidate operator with a require preference and that candidate does not have a prohibit preference then that candidate is the winner and preference semantics terminates 167 168 APPENDIX D THE RESOLUTION OF OPERATOR PREFERENCES Preference resolution all operator preferences are input to the resolution procedure All operator preferences else all acceptable candidates are passed on all nonprohibited candidates are passed on all nonrejected candidates are passed on pass along only candidates that are better if none pass on those that are not worse pass along only candidates that are best if none pass on all candidates all nonworst candidates are passed on RequireTest AcceptableCollect ProhibitFilter RejectFilter BetterWorseFilter BestFilter IndifferentTest each step may add or remove some operator candidates only some steps may exit one required operator multiple required operators required is also prohibited one candidate remaining no candidates remaining one operator both better and worse than another two operators better than each other two operators worse
120. er removes the candidates that have reject preferences in memory e At this point if the set of remaining candidates is either empty or has one member preference semantics terminates and this set is returned e Otherwise the remaining candidates are passed to the BetterWorseFilter BetterWorseFilter gt lt This filter checks for better worse conflicts and oth erwise filters out candidates based on better and worse preferences e A better worse conflict occurs when one candidate has both better and worse preferences with respect to another operator i e A lt B amp B lt A Since preferences are not transitive the situation A lt B lt C lt A is not a conflict If there are better worse conflicts preference semantics ter minates by declaring a conflict impasse and returning the set of conflicted items e Otherwise Filter out of the candidates the ones that have another can didate that is better or are worse than another candidate The resulting candidates are passed to the BestFilter BestFilter gt If some remaining candidate has a best preference this filter re moves any candidates that do not have a best preference If there are no best preferences for any of the current candidates the filter has no effect The re maining candidates are passed to the WorstFilter WorstFilter lt If all remaining candidates have worst preferences this filter has no effect Otherwise the filter removes any candidate
121. erator The conditions establish that 1 An operator has been selected for the current state a the operator is named move block b the operator has a moving block and a destination 2 The state has an ontop relation a the ontop relation has a top block that is the same as the gt moving block of the operator b the ontop relation has a bottom block that is different from the gt destination of the operator The actions 1 create a reject preference for the ontop relation sp blocks world apply move block remove old ontop state lt s gt operator lt o gt ontop lt ontop gt lt o gt name move block moving block lt block1 gt destination lt block2 gt lt ontop gt top block lt block1 gt pottom block lt gt lt block2 gt lt block3 gt SD lt s gt ontop lt ontop gt HHEHHEHHHHHHHEHEAHHHEH HEHEHE HEHEHE HEH HEHEHE HEHE HAA HEHEHE HHRH HEHE RHEE HH Apply a MOVE BLOCK operator the block is now ontop of the destination This production is part of the application of a move block operator The conditions establish that 1 An operator has been selected for the current state a the operator is named move block b the operator has a moving block and a destination The actions 1 create an acceptable preference for a new ontop relation create acceptable preferences for the substructure of the ontop relation the top
122. ere are differences in the preference mechanism and in operator termination among other things between Soar 8 and Soar 7 Users should read the Soar 8 2 Release Notes for more details Warnings Production memory and working memory must be empty to switch between modes 5 4 15 timers Toggle on or off the internal timers used to profile Soar Synopsis timers ed Options d disable off Disable all timers e enable on Enable timers as compiled Description This command is used to control the timers that collect internal profiling information while Soar is running With no arguments this command prints out the current timer status Timers are ENABLED by default The default compilation flags for soar enable the basic timers and disable the detailed timers The timers command can 136 CHAPTER 5 THE SOAR USER INTERFACE only enable or disable timers that have already been enabled with compiler directives See the stats command for more info on the Soar timing system See Also stats 5 4 16 waitsnc Synopsis wait eld Options e enable on Turns a state no change into a wait state d disable off Default A state no change generates an impasse Description In some systems espcially those that model expert fully chunked knowledge a state no change may represent a wait state rather than an impasse The waitsnc command allows the user to switch
123. evaluated productions that 2 the preferences are retract are no a evaluated 3 a new operator is selected instantiated are retracted 3 elements are added and a new state is created deleted from working memory Figure 2 8 A detailed illustration of Soar s decision cycle out of date 2 6 1 Impasse Types There are four types of impasses that can arise from the preference scheme Tie impasse A tie impasse arises if the preferences do not distinguish between two or more operators with acceptable preferences If two operators both have best or worst preferences they will tie unless additional preferences distinguish between them 24 CHAPTER 2 THE SOAR ARCHITECTURE Soar while HALT not true Cycle Cycle InputPhase ProposalPhase DecisionPhase ApplicationPhase OutputPhase ProposalPhase while some I supported productions are waiting to fire or retract FireNewlyMatchedProductions RetractNewlyUnmatchedProductions DecisionPhase for each state in the stack starting with the top level state until a new decision is reached EvaluateOperatorPreferences for the state being considered if one operator preferred after preference evaluation SelectNewOperator else could be no operator available or CreateNewSubstate unable to decide between more than one ApplicationPhase while some productions are waiting to fire or retract FireNewlyMatchedProductions RetractNewlyUnmatchedProductions
124. eviously been inspected 6 S append S elaborate_ GDS c compute GDS dependencies for c and add to goal s GDS Cinspected true c s context dependencies have been added to the GDS no need to consider it again for this GDS return S the list of new dependencies in the GDS END PROC GoalLevel assertion A Return the goal level associated with assertion A Figure E 3 The algorithm for determining members of the GDS INSERT DIAGRAM HERE Figure E 4 The GDS and WME data structures Other implementation issues e Allocating memory for the GDS The GDS memory is created for each goal when the goal is created The GDS is deallocated when the goal is removed A NIL WME pointer for the GDS indicates a goal has no WMEs in its GDS e Updating a WME GDS pointer A WME should appear in only the GDS of the highest goal for which it is 179 dependent If a WME is determined to already be in a GDS lower than the current goal its GDS pointer is updated to the higher goal it is removed from the gds_WME DLL of the lower goal and added to the higher one If there are no other WMEs on the gds_WME DLL of the lower goal its WME pointer is set to NIL the GDS itself is retained because we don t want to have to reallocate memory for the GDS if we need to add to it later 180 APPENDIX E A GOAL DEPENDENCY SET PRIMER INDEX Index 58 167 amp 58 48 58 168 46 58 168 Ol lt 43 58 168
125. ference states that the value is not a candidate for selection Better gt Worse lt A better or worse preference states for the two values involved that one value should not be selected if the other value is a candidate Better and worse allow for the creation of a partial ordering between candidate values Better and worse are simple inverses of each other so that A better than B is equivalent to B worse than A Best gt A best preference states that the value may be better than any compet ing value unless there are other competing values that are also best If a value is best and not rejected prohibited or worse than another it will be selected over any other value that is not also best or required If two such values are best then any remaining preferences for those candidates worst indifferent will be examined to determine the selection Note that if a value that is not rejected or prohibited is better than a best value the better value will be selected This result is counter intuitive but allows explicit knowledge about the relative worth of two values to dominate knowl edge of only a single value A require preference should be used when a value must be selected for the goal to be achieved Worst lt A worst preference states that the value should be selected only if there are no alternatives It allows for a simple type of default specification The semantics of the worst preference are similar to those
126. from A to A is a dependent change for feature 1 because A was used to create 1 In Soar 7 some features are insensitive to dependent changes These features are often referred to as persistent WMEs because unlike i supported WMEs they remain in memory until explicitly removed There are two different types of this stronger persistence o support and c support Any feature created by the action of an operator receives operator support An o supported feature remains in memory until explicitly rejected or until the super structure to which it is attached is removed Removal is architecturally independent of the WME s instantiating conditions Context support affects the persistence of an operator itself rather than its effects Once a unique operator has been chosen by the decision procedure the choice persists until explicitly re decided via a reconsider preference C support ensures that the WME for a selected operator remains available even if the production that proposed the operator is no longer instantiated Soar 8 eliminates c support so that operators now persist only as long as they receive instantiation support This change was integral to the overall solution Soar 8 provides but is distinct from the GDS The GDS provides a solution to the first problem When A changes the persistent WME 1 may be no longer consistent with its context e g A The specific solution is inspired by the chunking algorithm In S
127. g is optional Its absence is equivalent to t both Description This commands allows users to improve state tracing by issuing filter options that are applied when watching wmes Users can selectively define which object attribute value triplets are monitored and whether they are monitored for addition removal or both as they go in and out of working memory Note The functionality of watch wmes resided in the watch command prior to Soar 8 6 Examples Users can watch an attribute of a particular object as long as that object already exists soar gt watch wmes add filter t both D1 speed or print WMEs that retract in a specific state provided the state already exists soar gt watch wmes add filter t removes S3 120 CHAPTER 5 THE SOAR USER INTERFACE or watch any relationship between objects soar gt watch wmes add filter t both ontop 5 4 Configuring Soar s Runtime Parameters This section describes the commands that control Soar s Runtime Parameters Many of these commands provide options that simplify or restrict runtime behavior to en able easier and more localized debugging Others allow users to select alternative algorithms or methodologies Users can configure Soar s learning mechanism exam ine the backtracing information that supports chunks and justifications provide hints that could improve the efficiency of the Rete matcher limit runaway chunking and production firing choose an alte
128. g of type block 3 There is no ontop relation having the block as its bottom block The action 1 create an acceptable preference for an attribute value pair asserting the block is clear This production will retract whenever an ontop relation for the given block 159 is created Since the lt block gt clear yes wme only has i support it will be removed from working memory automatically when the production retracts sp elaborate block clear state lt s gt problem space blocks thing lt block gt lt block gt type block lt ontop gt bottom block lt block gt S gt lt block gt clear yes HHEHHHHAHHHHAAHHHAAAH HERA EH HAA AHA AHH HAR AHA A RRA A HEAR AAA RAHA Suggest MOVE BLOCK operators This production proposes operators that move one block ontop of another block The conditions establish that 1 The state has a problem space named blocks 2 The block moved and the block moved TO must be both be clear The block moved is different from the block moved to The block moved must be type block The block moved must not already be ontop the block being moved to The actions create an acceptable preference for an operator 2 create acceptable preferences for the substructure of the operator its name its moving block and the destination oF Ww m sp blocks world propose move block state
129. h and fire again on each cycle as long as it remains in working memory to get the production to refire the structure must be removed and added again 3 5 3 Input and output in production memory Productions involved in input will test for specific attributes and values on the input link while productions involved in output will create preferences for specific attributes and values on the output link For example a simplified production that responds to the vision input for the blocks task might look like this sp blocks world elaborate input state lt s gt io input link lt in gt lt in gt block lt ib1 gt lt ib1 gt x location lt x1 gt y location lt y1 gt lt in gt block lt ib2 gt lt gt lt ib1 gt lt ib2 gt x location lt x1 gt y location lt y2 gt gt lt y1 gt gt lt s gt block lt b1 gt lt s gt block lt b2 gt lt b1 gt x location lt x1 gt y location lt y1 gt clear no lt b2 gt x location lt x1 gt y location lt y2 gt above lt b1 gt This production copies two blocks and their locations directly to the top level state It also adds information about the relationship between the two blocks The variables used for the blocks on the RHS of the production are deliberately different from the variable name used for the block on the input link in the LHS of the production If the variable were the same the production would create
130. h is related to watch but applies only to specific named productions firing counts and stats are useful for understanding how much work Soar is doing chunk name format is less frequently used but allows for detailed control of Soar s chunk naming 5 3 1 chunk name format Specify format of the name to use for new chunks Synopsis chunk name format sl p lt prefix gt chunk name format sl c lt count gt Options s short Use the short format for naming chunks 1 long Use the long format for naming chunks default p prefix lt prefix gt If lt prefix gt is given use lt prefix gt as the prefix for nam ing chunks Otherwise return the current prefix de faults to chunk c count lt count gt If lt count gt is given set the chunk counter for naming chunks to lt count gt Otherwise return the current value of the chunk counter Description The short format for naming newly created chunks is prefixChunknum The long default format for naming chunks is prefix Chunknum ddc impassetype dcChunknum where prefix is a user definable prefix string prefix defaults to chunk when unspecified by the user It may not contain the character Chunknum is lt count gt for the first chunk created lt count gt 1 for the second chunk created etc dc is the number of the decision cycle in which the chunk was formed impassetype is one of tie
131. hange impasse An operator no change impasse can be resolved by productions that apply the operator changing the state so the operator proposal no longer matches or other operators are proposed and preferred Eliminating Impasses An impasse is resolved when results are created that allow progress to be made in the state where the impasse arose In Soar an impasse can be eliminated but not resolved when a higher level impasse is resolved eliminated or regenerated In these cases the impasse becomes irrelevant because higher level processing can proceed An impasse can also become irrelevant if input from the outside world changes working memory which in turn causes productions to fire that make it possible to select an operator In all these cases the impasse is eliminated but not resolved and Soar does not learn in this situation Regenerating Impasses An impasse is regenerated when the problem solving in the subgoal becomes inconsis tent with the current situation During problem solving in a subgoal Soar monitors which aspect of the surrounding situation the working memory elements that exist in 30 CHAPTER 2 THE SOAR ARCHITECTURE superstates the problem solving in the subgoal has depended upon If those aspects of the surronding situation change either because of changes in input or because of results the problem solving in the subgoal is inconsistent and the state created in response to the original impasse is remo
132. he internal flag is used in which case the wmes themselves are printed identifier attribute value The pattern is surrounded by parentheses The identifier attribute and value must be valid Soar symbols or the wildcard symbol which matches all occurences The optional symbol restricts pattern matches to acceptable preferences Examples Print the working memory elements and their timetags which have the identifier s1 as object and v2 as value print internal s1 v2 Print the Soar stack which includes states and operators print stack Print the named production in its RETE form print if prodname Print the names of all user productions currently loaded print u Default Aliases Alias Maps to p print pc print chunks wmes print i 5 2 EXAMINING MEMORY 105 See Also default wme depth predefined aliases 5 2 8 production find Synopsis production find lrs n c pattern Options c chinks Look only for chunks that match the pattern 1 lhs Match pattern only against the conditions left hand side of productions default n nochunks Disregard chunks when looking for the pattern r rhs Match pattern against the actions right hand side of productions s show bindings Show the bindings associated with a wildcard pattern pattern Any pattern that can appear in productions Description The production find c
133. he chunks allowing higher level subgoals to be chunked 3 The chunk duplicates a production or chunk already in production memory In some rare cases a duplicate production will not be detected because the order of the conditions or actions is not the same as an existing production 4 The augmentation quiescence t of the substate that produced the result is backtraced through This mechanism is motivated by the chunking from exhaustion problem where the results of a subgoal are dependent on the exhaustion of alternatives see Section 4 6 on page 80 If this substate augmentation is encountered when determining the conditions of a chunk then no chunk will be built for the currently considered action This is recursive so that if an un chunked result is relevant to a second result no chunk will be built for the second result This does not prevent the creation of a chunk that would include quiescence t as a condition 5 Learning has been temporarily turned off via a call to the dont learn produc tion action described on page 65 in Section 3 3 6 12 This capability is provided for debugging and system development and it is not part of the theory of Soar If a result is to be chunked Soar builds the chunk as soon as the result is created rather than waiting until subgoal termination 4 2 Determining Conditions and Actions Chunking is an experience based learning mechanism that summarizes as productions the problem so
134. he preferences wme support for all WMEs comprising the specified ID Note For the time being numeric indifferent preferences are listed under the heading binary indifferents Examples This example prints the preferences on S1 operator and the production names which created the preferences 5 2 EXAMINING MEMORY 101 soar gt preferences S1 operator names Preferences for S1 operator acceptables 02 fill From waterjug propose fill 03 fill From waterjug propose fill unary indifferents 02 fill From waterjug propose fill 03 fill From waterjug propose fill If the current state is S1 then the above syntax is equivalent to preferences n This example shows the support for the WMEs with the jug attribute soar gt preferences s1 jug Preferences for S1 jug acceptables S1 jug I4 0 S1 jug J1 0 This example shows the support for the WMEs with lt value gt J1 and the produc tions that generated them soar gt pref J1 1 Support for 31 03 jug J1 03 jug J1 From water jug propose fill Support for 11 S1 jug J1 S1 jug J1 0 From water jug apply initialize water jug look ahead This example shows the support for all WMEs that make up the object S1 soar gt pref o s1 Support for S1 problem space S1 problem space P1 Support for S1 name S1 name water jug 0 Support for S1 jug Si jug I4 0 S1 jug J1 0 Support for S1
135. hen save backtraces is set to on backtracing information can be retrieved by using the explain backtraces command Saving backtracing information may slow down the execution of your Soar program but it can be a very useful tool in understanding how chunks are formed See Also explain backtraces 5 4 13 set stop phase Controls the phase where agents stop when running by decision Synopsis set stop phase ABadiop Options Options A and B are optional and mutually exclusive If not specified the default is B Only one of a d i o p must be selected With no options reports the current stop phase 134 CHAPTER 5 THE SOAR USER INTERFACE A after Stop after specified phase B before Stop before specified phase the default a apply Select the apply phase d decision Select the decision phase i input Select the input phase 0 output Select the output phase p proposal Select the proposal phase Description When running by decision cycle it can be helpful to have agents stop at a particular point in its execution cycle This command allows the user to control which phase Soar stops in The precise definition is that running for lt n gt decisions and stopping before phase lt ph gt means to run until the decision cycle counter has increased by lt n gt and then stop when the next phase is lt ph gt The phase sequence as of this writing is
136. her Decision or Output even if quiescence has not been reached Examples The command issued with no arguments returns the max elaborations allowed max elaborations to set the maximum number of elaborations in one phase to 50 max elaborations 50 5 4 7 max memory usage Set the number of bytes that when exceeded by an agent will trigger the memory usage exceeded event Synopsis max memory usage n Options n Size of limit in bytes 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 129 Description The max memory usage command is used to trigger the memory usage exceeded event The initial value of this is 100MB 100 000 000 allowable settings are any integer greater than 0 The code supporting this event is commented out by default in the release build The test can be computationally expensive and is needed only for specific embedded applications Users may enable the test and event generation by uncommenting code in SoarKernel src mem cpp Using the command with no arguments displays the current limit 5 4 8 max nil output cycles Limit the maximum number of decision cycles that are executed without producing output when run is invoked with run til output args Synopsis max nil output cycles n Options n Maximum number of consecutive output cycles allowed without producing output Must be a positive integer Description This command sets and prints the maximum
137. here a plus sign follows the value test state identifier test operator valuel test In the remainder of this section we describe the different tests that can be used for identifiers attributes and values The simplest of these is a constant where the constant specified in the attribute or value must match the same constant in a working memory element 3 3 5 2 Variables in productions Variables match against constants in working memory elements in the identifier at tribute or value positions Variables can be further constrained by additional tests 3 3 PRODUCTION MEMORY 43 described in later sections or by multiple occurrences in conditions If a variable oc curs more than once in the condition of a production the production will match only if the variables match the same identifier or constant However there is no restriction that prevents different variables from binding to the same identifier or constant Because identifiers are generated by Soar at run time it impossible to include tests for specific identifiers in conditions Therefore variables are used in conditions whenever an identifier is to be matched Variables also provide a mechanism for passing identifiers and constants which match in conditions to the action side of a rule Syntactically a variable is a symbol that begins with a left angle bracket i e lt ends with a right angle bracket i e gt and contains at least one alphanumeric
138. hrough wmes created via add wme nor will such wmes ever be removed thru Soar s garbage collec tion Manually removing context impasse wmes may have unexpected side effects See Also remove wine 5 6 2 remove wme Manually remove an element from working memory Synopsis remove wme timetag Options timetag A positive integer matching the timetag of an existing working memory element 150 CHAPTER 5 THE SOAR USER INTERFACE Description The remove wme command removes the working memory element with the given timetag This command is provided primarily for use in Soar input functions al though there is no programming enforcement remove wme should only be called from registered input functions to delete working memory elements on Soar s input link Beware of weird side effects including system crashes Default Aliases Alias Maps to rw remove wme See Also add wme Warnings remove wme should never be called from the RHS if you try to match a wme on the LHS of a production and then remove the matched wme on the RHS Soar will crash If used other than by input and output functions interfaced with Soar this command may have weird side effects possibly even including system crashes Removing input wmes or context impasse wmes may have unexpected side effects You ve been warned 5 7 Miscellaneous The specific commands described in this section are Summary
139. ht be considered in solving a problem that is they define the problem space Soar programs are implicitly organized in terms of problem spaces because the con ditions for proposing operators will restrict an operator to be considered only when it is relevant The complete problem space for the blocks world is show in Figure 2 6 Typically when Soar solves a problem in this problem space it does not explicitly generate all of the states examine them and then create a path Instead Soar is in a specific state at a given time represented in working memory attempting to select an operator that will move it to a new state It uses whatever knowledge it has about selecting operators given the current situation and if its knowledge is sufficient it will move toward its goal The same problem could be recast in Soar as a planning problem where the goal is to develop a plan to solve the problem instead of just solv 14 CHAPTER 2 THE SOAR ARCHITECTURE ing the problem In that case a state in Soar would consist of a plan which in turn would have representations of Blocks World states and operators from the original space The operators would perform editing operations on the plan such as adding new Blocks World operators simulating those operators etc In both formulations of the problem Soar is still applying operators to generate new states it is just that the states and operators have different content The remaining sections in this
140. ibute Options 0 n none Print just the preferences themselves 1 N names Print the preferences and the names of the productions that generated them 2 t timetags Print the information for the names option above plus the timetags of the wmes matched by the indicated pro ductions 3 w wmes Print the information for the timetags option above plus the entire wme 0 object Print the support for all the wmes that comprise the object the specified ID id Must be an existing Soar object identifier attribute Must be an existing attribute of the specified identifier Description The preferences command prints all the preferences for the given object id and attribute If id and attribute are not specified they default to the current state and the current operator The is optional when specifying the attribute The optional arguments indicates the level of detail to print about each preference This command is useful for examining which candidate operators have been proposed and what relationships if any exist among them If a preference has O support the string O will also be printed When only the ID is specified on the commandline if the ID is a state Soar uses the default attribute operator If the ID is not a state Soar prints the support information for all WMEs whose lt value gt is the ID When an ID and the object flag are specified Soar prints t
141. ibutes and values have no meaning to the Soar architecture aside from a few WME s created by the architecture itself For example Soar doesn t care whether the things in the blocks world are called blocks or cubes or chandeliers It is up to the Soar programmer to pick suitable labels and to use them consistently The elements in working memory arise from one of four sources 1 The actions of productions create most working memory elements 2 The decision procedure automatically creates some special state augmentations type superstate impasse whenever a state is created States are created during initialization the first state or because of an impasse a substate 3 The decision procedure creates the operator augmentation of the state based on preferences This records the selection of the current operator 4 External I O systems create working memory elements on the input link for sensory data The elements in working memory are removed in six different ways 1 The decision procedure automatically removes all state augmentations it creates when the impasse that led to their creation is resolved Tn order to allow these links to have some substructure the attribute name may be an identifier which means that the attribute may itself have attributes and values as specified by additional working memory elements 16 CHAPTER 2 THE SOAR ARCHITECTURE 2 The decision procedure removes the operator aug
142. iew of how input and output appear in working memory is presented in the fifth section the full discussion of Soar I O can be found in the SML Quick Start Guide This chapter assumes that you understand the operating principles of Soar as pre sented in Chapter 2 3 1 Working Memory Working memory contains working memory elements WME s As described in Section 2 2 WME s can be created by the actions of productions the evaluation of preferences the Soar architecture and via the input output system A WME is a list consisting of three symbols an identifier an attribute and a value where the entire WME is enclosed in parentheses and the attribute is preceded by an up arrow A template for a working memory element is identifier attribute value The identifier is an internal symbol generated by the Soar architecture as it runs The attribute and value can be either identifiers or constants if they are identifiers there are other working memory elements that have that identifier in their first position As the previous sentences demonstrate identifier is used to refer both to the first 33 34 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS position of a working memory element as well as to the symbols that occupy that position 3 1 1 Symbols Soar distinguishes between two types of working memory symbols identifiers and constants Identifiers An identifier is a unique symbol created at runtime when a new object
143. ifier and the tests for augmentations of that identifier in terms of attributes and values The condition is terminated with a close parenthesis Thus a single condition might test properties of a single working memory element or properties of multiple working memory elements that constitute an object identifier test attributei test valuei test attribute2 test value2 test attribute3 test value3 test kad The first condition in a production must match against a state in working memory Thus the first condition must begin with the additional symbol state All other conditions and actions must be linked directly or indirectly to this condition This linkage may be direct to the state or it may be indirect through objects specified in the conditions If the identifiers of the actions are not linked to the state a warning is printed when the production is parsed and the production is not stored in production memory In the actions of the example production shown in Figure 3 2 the operator preference is directly linked to the state and the remaining actions are linked indirectly via the operator preference Although all of the attribute tests in the template above are followed by value tests it is possible to test for only the existence of an attribute and not test any specific value by just including the attribute and no value Another exception to the above template is operator preferences which have the following structure w
144. ing T1 36 8 Ti 1 S1 S1 S1 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS thing B1 thing B2 type state This shows all the individual augmentations of S1 each is preceded by an integer tametag 3 1 4 Acceptable preferences in working memory The acceptable preferences for the operator augmentations of states appear in working memory as identifier attribute value preference quadruples No other preferences ap pear in working memory A template for an acceptable preference in working memory 1S identifier operator value For example if you run Soar with the example blocks world program described in Appendix A after the first operator has been selected you can again look at the top level state using the wmes command soar gt wmes sl 37 S1 io 11 9 S1 ontop 03 10 11 48 49 50 51 54 52 53 4 2 5 8 6 7 1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 S1 ontop 02 ontop 01 operator 04 operator 05 operator 06 operator 07 operator 07 operator 08 operator 09 problem space blocks superstate nil thing T1 thing B1 thing B3 thing B2 type state The state S1 has six augmentations of acceptable preferences for different operators 04 through 09 These have plus signs following the value to denote that they are acceptable preferences The state has exactly on
145. input proposal decision apply output Stopping after one phase is exactly equivalent to stopping before the next phase On initialization Soar defaults to stopping before the input phase or after the output phase however you like to think of it Setting the stop phase applies to all agents Examples set stop phase Bi stop before input phase set stop phase Ad stop after decision phase before apply phase set stop phase d stop before decision phase set stop phase after output stop after output phase set stop phase reports the current stop phase 5 4 14 soars Toggle between Soar 8 methodology and Soar 7 methodology Synopsis soar8 ed 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 135 Options e enable on Use Soar 8 methodology Default d disable off Use Soar 7 methodology Description The soar8 command allows users to revert to Soar 7 methodology in order to run older Soar programs Both production memory and working memory must be empty to toggle between Soar 7 and Soar 8 mode The soar8 command with no arguments returns the current mode the default is Soar 8 Users can toggle between modes ONLY when production memory and working memory are both empty This means that users must either change the mode at startup before any productions are loaded or must first issue excise all which does an init soar as well before changing modes Note that th
146. ion of the blocks world This blocks world program is used as an example throughout the manual Appendix B provides a grammar for Soar productions Appendix C describes the determination of o support Appendix D provides a detailed explanation of the preference resolution process Appendix E provides an explanation of the Goal Dependency Set Additional Back Matter The appendices are followed by an index the last pages of this manual contain a summary and index of the user interface functions for quick reference Not Described in This Manual Some of the more advanced features of Soar are not described in this manual such as how to interface with a simulator or how to create Soar applications using multiple interacting agents A discussion of these topics is provided in a separate document the SML Quick Start Guide 1 2 CONTACTING THE SOAR GROUP 3 For novice Soar users try The Soar 8 Tutorial which guides the reader through several example tasks and exercises See Section 1 2 for information about obtaining Soar documentation 1 2 Contacting the Soar Group Resources on the Internet The primary website for Soar is http sitemaker umich edu soar Look here for the latest downloads documentation and Soar related announcements as well as links to information about specific Soar research projects and researchers and a FAQ list of frequently asked questions about Soar For questions about Soar you may write to the S
147. ion_name production_name excise acdtu Options a all Remove all productions from memory and perform an init soar com mand c chunks Remove all chunks learned productions and justifications from memory d default Remove all default productions default from memory t task Remove chunks justifications and user productions from memory u user Remove all user productions but not chunks or default rules from memory production name Remove the specific production with this name Description This command removes productions from Soar s memory The command must be called with either a specific production name or with a flag that indicates a particular group of productions to be removed Using the flag a or all also causes an init soar Examples This command removes the production my first production and all chunks excise my first production chunks This removes all productions and does an init soar excise all Default Aliases Alias Maps to ex excise 86 CHAPTER 5 THE SOAR USER INTERFACE See Also init soar 5 1 2 help Provide formatted usage information about Soar commands Synopsis help command_name Options command_name Print usage syntax for the command Description This command prints formatted help for the given command name Examples To see the syntax for the excise command
148. is an error There is currently not support for multiple logs in the command line interface and this would be an instance of multiple logs This command echos output both to the screen and to a file just like clog See also clog 5 5 4 dirs List the directory stack Synopsis dirs Options No options Description This command lists the directory stack Agents can move through a directory struc ture by pushing and popping directory names The dirs command returns the stack The command pushd places a new agent current directory on top of the directory stack and cd s to it The command popd removes the directory at the top of the 5 5 FILE SYSTEM I O COMMANDS 141 directory stack and cd s to the previous directory which now appears at the top of the stack See Also cd ls pushd popd source 5 5 5 echo Print a string to the current output device Synopsis echo string Options string The string to print Description This command echos the args to the current output stream This is normally stdout but can be set to a variety of channels If an arg is nonewline then no newline is printed at the end of the printed strings Otherwise a newline is printed after printing all the given args Echo is the easiest way to add user comments or identification strings in a log file Examples This example will add these comments to the screen and any open log file echo This is the fir
149. is possible for several working memory elements to share the same identifier and attribute but have different values Such attributes are called multi valued attributes or multi attributes For example state S1 above has two attributes that are multi valued thing and ontop 3 1 3 Timetags When a working memory element is created Soar assigns it a unique integer timetag The timetag is a part of the working memory element and therefore WME s are actually quadruples rather than triples However the timetags are not represented in working memory and cannot be matched by productions The timetags are used to distinguish between multiple occurrences of the same WME As preferences change and elements are added and deleted from working memory it is possible for a WME to be created removed and created again The second creation of the WME which bears the same identifier attribute and value as the first WME is different and therefore is assigned a different timetag This is important because a production will fire only once for a given instantiation and the instantiation is determined by the timetags that match the production and not by the identifier attribute value triples To look at the timetags of WMEs the wmes command can be used soar gt wmes sl 3 S1 io I1 10 S1 ontop 02 9 S1 ontop 03 11 S1 ontop 01 4 S1 problem space blocks 2 S1 superstate nil 6 S1 thing B3 5 S1 th
150. k is no longer clear 2 1 9 Problem Spaces If we were to construct a Soar system that worked on a large number of different types of problems we would need to include large numbers of operators in our Soar program For a specific problem and a particular stage in problem solving only a In this blocks world task the table always has room for another block so it is represented as always being clear 2 1 AN OVERVIEW OF SOAR 13 a B BI block move block move move move b A e nlog BC Al block block move block CA CT BT move block BT A A move block B B CA A B imeve ro re move loc joc move block AC AT Cn block or move bloc m A B move move block move block C T posk B A move block A BT move move block B block AT BT move B block A B _ IAI ag move block B move move AB block bloc CT AT States aA operators A Figure 2 6 The problem space in the blocks world includes all operators that move blocks from one location to another and all possible configurations of the three blocks subset of all possible operators are actually relevant For example if our goal is to count the blocks on the table operators having to do with moving blocks are probably not important although they may still be legal The operators that are relevant to current problem solving activity define the space of possible states that mig
151. lict when two or more objects are better than each other and they are not dominated by a third operator 3 constraint failure when there are conflicting necessity preferences 4 no change when the proposal phase runs to quiescence without suggesting a new operator The list below gives the seven augmentations that the architecture creates on the substate generated when an impasse is reached and the values that each augmentation can contain type state impasse Contains the impasse type tie conflict constraint failure or no change choices Either multiple for tie and conflict impasses constraint failure for constraint failure impasses or none for no change impasses superstate Contains the identifier of the state in which the impasse arose attribute For multi choice and constraint failure impasses this contains operator For no change impasses this contains the attribute of the last decision with a value state or operator item For multi choice and constraint failure impasses this contains all values in volved in the tie conflict or constraint failure If the set of items that tie or conflict changes during the impasse the architecture removes or adds the appropriate item augmentations without terminating the existing impasse quiescence States are the only objects with quiescence t which is an explicit statement that quiescence exhaustion of the elaboration cycle was reached in the supersta
152. line comments moving block lt thing1 gt destination lt thing2 gt When commenting out conditions or actions be sure that all parentheses remain balanced outside the comment External comments Comments may also appear in a file with Soar productions outside the curly braces of the sp command Comments must either start a new line with a or start with In both cases the comment runs to the end of the line imagine that this is part of a Soar program that contains Soar productions as well as some other code source blocks soar this is also a comment 3 3 5 The condition side of productions or LHS The condition side of a production also called the left hand side or LHS of the production is a pattern for matching one or more WMEs When all of the conditions of a production match elements in working memory the production is said to be instantiated and is ready to perform its action The following subsections describe the condition side of a production including predi 42 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS cates disjunctions conjunctions negations acceptable preferences for operators and a few advanced topics 3 3 5 1 Conditions The condition side of a production consists of a set of conditions Each condition tests for the existence or absence explained later in Section 3 3 5 6 of working memory elements Each condition consists of a open parenthesis followed by a test for the ident
153. lued attributes and attribute path notation Negations of multi valued attributes can be combined with attribute path notation However it is very easy to make mistakes when using negated multi valued attributes with attribute path notation Although it is possible to do it correctly we strongly discourage its use For example sp blocks negated conjunction example state lt s gt name top state ontop bottom object name table A gt lt s gt nothing ontop A or table true 54 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS gets expanded to sp blocks negated conjunction example state lt s gt name top state lt s gt ontop lt o 1 gt lt o 1 gt bottom object lt b 1 gt lt b 1 gt name A lt b 1 gt name table gt lt s gt nothing ontop A or table true This example does not refer to two different blocks with different names It tests that there is not an ontop relation with a bottom block that is named A and named table Thus this production probably should have been written as sp blocks negated conjunction example state lt s gt name top state ontop bottom object name table ontop bottom object name A gt lt s gt nothing ontop A or table true which expands to sp blocks negated conjunction example state lt s gt name top state lt s gt ontop lt o 2 gt lt o 2 gt bottom object lt b 2 gt lt b 2 gt name a
154. lved during the execution of a Soar program how they may be eliminated during execution 2 6 IMPASSES AND SUBSTATES 29 without being resolved and some tips on how to modify a Soar program to prevent a specific impasse from occurring in the first place Resolving Impasses An impasse is resolved when processing in a subgoal creates results that lead to the selection of a new operator for the state where the impasse arose When an operator impasse is resolved Soar has an opportunity to learn and the substate and all its substructure is removed from working memory Here are possible approaches for resolving specific types of impasses are listed below Tie impasse A tie impasse can be resolved by productions that create pref erences that prefer one option better best require eliminate alterna tives worse worst reject prohibit or make all of the objects indifferent indifferent Conflict impasse A conflict impasse can be resolved by productions that cre ate preferences to require one option require or eliminate the alternatives reject prohibit Constraint failure impasse A constraint failure impasse cannot be resolved by additional preferences but may be prevented by changing productions so that they create fewer require or prohibit preferences State no change impasse A state no change impasse can be resolved by pro ductions that create acceptable or require preferences for operators Operator no c
155. lving that occurs within a state In order to maintain a history of the processing to be used for chunking Soar builds a trace of the productions that fire in the subgoals This section describes how the relevant actions are determined how information is stored in a trace and finally how the trace and the actions together determine the conditions for the chunk In order for the chunk to apply at the appropriate time its conditions must test exactly those working memory elements that were necessary to produce the results of the subgoal Soar computes a chunk s conditions based on the productions that fire in the subgoal beginning with the results of the subgoal and then backtracing through the productions that created each result It recursively backtraces through the working memory elements that matched the conditions of the productions finding lFor some tasks bottom up chunking facilitates modelling power law speedups although its long term theoretical status is problematic 4 2 DETERMINING CONDITIONS AND ACTIONS 77 the actions that led to the WME s creation etc until conditions are found that test elements that are linked to a superstate 4 2 1 Determining a chunk s actions A chunk s actions are built from the results of a subgoal A result is any working memory element created in the substate that is linked to a superstate A working memory element is linked if its identifier is either the value of a superstate WME o
156. m block lt T gt name A name B name C name TABLE Achieved A B Cl HHHHHHAEHHHHHHHHHEHAAEAA AREA HHRH REE A RRR HHH HHA HARRAH HHHHHHAEHHHHHHHHHHRAAHAA ARH HHHRE RRR AR ERE EHH AAR HERR HHA H Monitor the state Print a message every time a block is moved H HH HH H OF The conditions establish that 1 An operator has been selected for the current state a the operator is named move block b the operator has a moving block and a destination 2 each block has a name The actions 1 print a message for the user that the block has been moved to the destination sp blocks world monitor move block state lt s gt operator lt o gt 162 APPENDIX A THE BLOCKS WORLD PROGRAM lt o gt name move block moving block lt block1 gt destination lt block2 gt lt block1 gt name lt blocki name gt lt block2 gt name lt block2 name gt gt write crlf Moving Block lt block1 name gt to lt block2 name gt Appendix B Grammars for production syntax This appendix contains the BNF grammars for the conditions and actions of produc tions BNF stands for Backus Naur form or Backus normal form consult a computer science book on theory programming languages or compilers for more information However if you don t already know what a BNF grammar is it s unlikely that you have any need for this appendix This information is provided for advan
157. mentation of the state when that operator is no longer selected as the current operator 3 Production actions that use reject preferences remove working memory ele ments that were created by other productions 4 The architecture automatically removes i supported WMEs when the produc tions that created them no longer match 5 The I O system removes sensory data from the input link when it is no longer valid 6 The architecture automatically removes WME s that are no longer linked to a state because some other WME has been removed For the most part the user is free to use any attributes and values that are appropriate for the task However states have special augmentations that cannot be directly created removed or modified by rules These include the augmentations created when a state is created and the state s operator augmentation that signifies the current operator and is created based on preferences The specific attributes that the Soar architecture automatically creates are listed in Section 3 4 Productions may create any other attributes for states Preferences are held in a separate preference memory where they cannot be tested by productions however acceptable preferences are held in both preference memory and in working memory By making the acceptable preferences available in working memory the acceptable preferences can be tested for in productions allowing the candidates operators to be compared before they are
158. mporarily stopped The default behavior of run with no arguments is to cause Soar to execute until it is halted or interrupted by an action of a production or until an external interrupt is issued by the user The run command can also specify that Soar should run only for a specific number of Soar cycles or phases which may also be prematurely stopped by a production action or the stop soar command This is helpful for debugging sessions where users may want to pay careful attention to the specific productions that are firing and retracting The run command takes optional arguments an integer count which specifies how many units to run and a units flag indicating what steps or increments to use If count is specified but no units are specified then Soar is run by decision cycles If units are specified but count is unpecified then count defaults to 1 The argument forever can be shortened to f is a keyword used instead of an integer count and indicates Soar should be run indefinitely until halted by problem solving completion or stopped by an interrupt If there are multiple Soar agents that exist in the same Soar process then issuing arun command in any agent will cause all agents to run with the same set of parameters unless the flag self is specified in which case only that agent will execute If an environment is registered for the kernel s update event then when the event it triggered the environment will get inf
159. nce for it specifically a preference to say that the value is a candidate for the operator attribute of a state this is done with either an acceptable or require preference There may also be others for example to say that the value is best The different preferences available and the semantics of preferences are explained in Section 2 4 1 Preferences remain in preference memory until removed for one of the reasons previously discussed in Section 2 3 3 2 4 1 Preference semantics This section describes the semantics of each type of preference More details on the preference resolution process are provided in Appendix D Only a single value can be selected as the current operator that is all values are mutually exclusive In addition there is no implicit transitivity in the semantics of preferences If A is indifferent to B and B is indifferent to C A and C will not be indifferent to one another unless there is a preference that A is indifferent to C or C and A are both indifferent to all competing values Acceptable An acceptable preference states that a value is a candidate for selection All values except those with require preferences must have an acceptable preference in order to be selected If there is only one value with an acceptable preference and none with a require preference that value will be selected as long as it does not also have a reject or a prohibit preference Reject A reject pre
160. nconsistency The fundamental problem is that the knowledge designer has to consider all possible interactions between all o supported WMEs and all contexts Soar systems often use the architecture s impasse mechanism to realize a form of decomposition These potential interactions mean that the knowledge de veloper cannot focus on individual problem spaces when creating knowledge which makes knowledge development more difficult Further in all but the simplest systems the knowledge designer will miss some potential interactions The result is agents are that were unnecessarily brittle failing in difficult to understand difficult to duplicate ways The GDS also solves the the problem of non contemporaneous constraints in chunks A non contemporaneous constraint refers to two or more conditions that never co occur simultaneously An example might be a driving robot that learned a rule that attempted to match red light and green light simultaneously Obviously for functioning traffic lights this rule would never fire By ensuring that local persistent elements are always consistent with the higher level context non contemporaneous constraints in chunks are guaranteed not to happen The GDS captures context dependencies during processing meaning the architecture will identify and respond to inconsistencies automatically The knowledge designer then does not have to consider potential inconsistencies between local o supported WMEs
161. ne when and how they should execute an action Generally input functions create and remove elements on the input link to update Soar s perception of the environment Output functions respond to values of working memory elements that appear on Soar s output link strucure 3 5 2 Input and output in working memory All input and output is represented in working memory as substructure of the io attribute of the top level state By default the architecture creates an input link attribute of the io object and an output link attribute of the io object The values of the input link and output link attributes are identifiers whose augmentations are the complete set of input and output working memory elements respectively Some Soar systems may benefit from having multiple input and output links or that use names which are more descriptive of the input or output function such as vision input link text input link or motor output link In addition to providing the default io substructure the architecture allows users to create multiple input and output links via productions and I O functions Any identifiers for io substructure created by the user will be assigned at run time and are not guaranteed to be the same from run to run Therefore users should always employ variables when referring to input and output links in productions Suppose a blocks world task is implemented using a robot to move actual blocks around with a camera creating input to So
162. ng 5 3 7 watch Control the run time tracing of Soar Synopsis watch watch level 0 1 2131415 watch N watch dpPwrDujcbi lt remove gt nlt f watch learning lt print noprint fullprint gt 114 CHAPTER 5 THE SOAR USER INTERFACE Options When appropriate a specific option may be turned off using the remove argument This argument has a numeric alias you can use 0 for remove A mix of formats is acceptable even in the same command line Basic Watch Settings Option Flag Argument Description to Option 1 level 0 to 5 see This flag is optional but recommended Set Watch a specific watch level using an integer 0 to 5 Levels this is an inclusive operation below N none No argu Turns off all printing about Soar s internals ment equivalent to level 0 d decisions remove Controls whether state and operator deci optional sions are printed as they are made p phases remove Controls whether decisions cycle phase optional names are printed as Soar executes P productions remove Controls whether the names of productions optional are printed as they fire and retract equiva lent to Dujc w wmes remove Controls the printing of working memory ele optional ments that are added and deleted as produc tions are fired and retracted Including wme changes to GDS r preferences remove Controls whether the preferences generated op
163. ng2 gt Thus several conditions may be collapsed into a single condition Using variables within structured value notation Variables are allowed within the parentheses of structured value notation to specify an identifier to be matched elsewhere in the production For example the variable lt ontop gt could be added to the conditions although it are not referenced again so this is not helpful in this instance sp blocks world propose move block state lt s gt problem space blocks thing lt thing1 gt lt gt lt thing1l gt lt thing2 gt ontop lt ontop gt top block lt thing1 gt pottom block lt gt lt thing2 gt lt thing1 gt type block clear yes lt thing2 gt clear yes gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt destination lt thing2 gt 56 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS Structured values may be nested to any depth Thus it is possible to write our example production using a single condition with multiple structured values sp blocks world propose move block state lt s gt problem space blocks thing lt thing1 gt lt gt lt thingi gt lt thing2 gt clear yes ontop top block lt thing1 gt type block clear yes pottom block lt gt lt thing2 gt gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt
164. nstant is truncated to only the integer portion This function essentially operates as a type casting function For example the expression 2 sqrt 6 could be printed as an integer using the following sp a write 2 int sqrt 6 float Converts a single symbol to a floating point constant This function expects either an integer constant symbolic constant or floating point constant The symbolic constant must be a string which can be interpreted as a single floating point number This function essentially operates as a type casting function For example if you wanted to print out an integer expression as a floating point number you could do the following sp gt write float 2 3 3 3 PRODUCTION MEMORY 63 3 3 6 10 Generating and manipulating symbols A new symbol an identifier is generated on the right hand side of a production whenever a previously unbound variable is used This section describes other ways of generating and manipulating symbols on the right hand side timestamp This function returns a symbol whose print name is a representation of the current date and time For example sp gt write timestamp When this production fires it will print out a representation of the current date and time such as soar gt runie 8 1 96 15 22 49 make constant symbol This function returns a new constant symbol guar anteed to be different from all symbols currently p
165. oar 8 whenever an o supported WME is created in the local state the superstate dependencies of that new feature are determined and added to the goal dependency set GDS of that state Conceptu ally speaking whenever a working memory change occurs the dependency sets for every state in the context hierarchy are compared to working memory changes If a removed element is found in a GDS the state is removed from memory along with all existing substructure The dependency set includes only dependencies for o supported features For example in Figure E 2 at time to because only i supported features have been created in the subgoal the dependency set is empty Three types of features can be tested in the creation of an o supported feature Each requires a slightly different type of update to the dependency set Elements in the superstate WMEs in the superstate are added directly to the goal s dependency set In Figure E 2 the persistent subgoal item 3 is dependent 4The implementation is slightly different trading additional memory overhead to avoid scanning all the goal dependency sets after each WM change See the next section 175 Dependency Set to ti A D t2 A B C D t3 A B C D Figure E 2 The Dependency Set in Soar 8 upon A and D These superstate WMEs are added to the subgoal s dependency set when 3 is added to working memory a
166. oar e mail list at soar group lists sourceforge net If you would like to be on this list yourself visit http lists sourceforge net lists listinfo soar group To report Soar bugs to check whether a bug has been reported or to check the status of a previously reported bug visit https winter eecs umich edu soar bugzilla For Those Without Internet Access If you cannot reach us on the internet please write to us at the following address The Soar Group Artificial Intelligence Laboratory University of Michigan 1101 Beal Ave Ann Arbor MI 48109 2110 USA 4 CHAPTER 1 INTRODUCTION 1 3 A Note on Different Platforms and Operating Systems Soar runs on a wide variety of computers including Unix and Linux machines Macintoshes running OSX and PCs running the Windows XP and probably 2000 and NT operating system This manual documents Soar generally although all references to files and directories use Unix format conventions rather than Windows style folders Chapter 2 The Soar Architecture This chapter describes the Soar architecture It covers all aspects of Soar except for the specific syntax of Soar s memories and descriptions of the Soar user interface commands This chapter gives an abstract description of Soar It starts by giving an overview of Soar and then goes into more detail for each of Soar s main memories working memory production memory and preference memory and processes the decision
167. omatic subgoaling and a single learning mechanism chunking All decisions are made through the combination of relevant knowledge at run time In Soar every decision is based on the current interpretation of sensory data and any relevant knowledge retrieved from permanent memory Decisions are never precompiled into uninterruptible sequences 2 CHAPTER 1 INTRODUCTION 1 1 Using this Manual We expect that novice Soar users will read the manual in the order it is presented Chapter 2 and Chapter 3 describe Soar from different perspectives Chapter 2 describes the Soar architecture but avoids issues of syntax while Chapter 3 describes the syntax of Soar including the specific conditions and actions allowed in Soar productions Chapter 4 describes chunking Soar s learning mechanism Not all users will make use of chunking but it is important to know that this capability exists Chapter 5 describes the Soar user interface how the user interacts with Soar The chapter is a catalog of user interface commands grouped by functionality The most accurate and up to date information on the syntax of the Soar User Interface is found online on the Soar Wiki at http winter eecs umich edu soarwiki Advanced users will refer most often to Chapter 5 flipping back to Chapters 2 and 3 to answer specific questions There are several appendices included with this manual Appendix A contains an example Soar program for a simple vers
168. ommand is used to find productions in production memory that include conditions or actions that match a given pattern The pattern given specifies one or more condition elements on the left hand side of productions or negated conditions or one or more actions on the right hand side of productions Any pattern that can appear in productions can be used in this command In addition the asterisk symbol can be used as a wildcard for an attribute or value It is important to note that the whole pattern including the parenthesis must be enclosed in curly braces for it to be parsed properly The variable names used in a call to production find do not have to match the variable names used in the productions being retrieved The production find command can also be restricted to apply to only certain types of productions or to look only at the conditions or only at the actions of productions by using the flags Examples Find productions that test that some object gumby has an attribute alive with value t In addition limit the rules to only those that test an operator named foo 106 CHAPTER 5 THE SOAR USER INTERFACE production find lt state gt gumby lt gv gt operator name foo lt gv gt alive t Note that in the above command lt state gt does not have to match the exact variable name used in the production Find productions that propose the operator foo production find rhs lt x gt operator lt op gt lt
169. on and add it to production 90 memory stats Print information on Soar s runtime statistics 110 stop soar Interrupt a running Soar program 92 time Use the system clock to record the time required 154 to execute the next command timers Toggle on or off the internal timers used to pro 135 file Soar version Print the version information for the Soar kernel 156 waitsnc Generate a wait state rather than a state no 136 change impasse warnings Toggle whether or not warnings are printed 113 watch Control the information printed as Soar runs 113 watch wmes Trace WMEs matching specific patterns 118
170. on cycles The total number of elaboration cycles that were executed during the run the everage number of elaboration cycles per decision cycle and the average time per elaboration cycle in mil liseconds This is not the total number of production firings as pro ductions can fire in parallel Production Firings The total number of productions that were fired Working Memory Changes This is the total number of changes to working memory This includes all additions and deletions from working memory Also prints the average match time Working Memory Size This gives the current mean and maximum number of working memory elements The optional stats argument memory provides information about memory usage and Soar s memory pools which are used to allocate space for the various data struc tures used in Soar The optional stats argument rete provides information about node usage in the Rete net the large data structure used for efficient matching in Soar Default Aliases Alias Maps to st stats See Also timers A Note on Timers The current implementation of Soar uses a number of timers to provide time based statistics for use in the stats command calculations These timers are 112 CHAPTER 5 THE SOAR USER INTERFACE total CPU time total kernel time phase kernel time per phase phase callbacks time per phase input function time output function time Total CPU time is calculate
171. one decision cycle and then move to the next agent When an agent generates output for the 3rd time it no longer runs even if other agents continue The interleave parameter must always be equal to or smaller than the specified run parameter This option is not currently compatible with the forever option Note If Soar has been stopped due to a halt action an init soar command must be issued before Soar can be restarted with the run command Default Aliases Alias Maps to d run d 1 e run e 1 step run 1 5 1 6 sp Define a Soar produ Synopsis ction sp production_body Options production_body A Soar production Description The sp command c production_body is a reates a new production and loads it into production memory single argument parsed by the Soar kernel so it should be en closed in curly braces to avoid being parsed by other scripting languages that might be in the same proces The overall syntax of a rule is as follows name documentation string 5 1 BASIC COMMANDS FOR RUNNING SOAR 91 FLAG LHS gt RHS The first element of a rule is its name Conventions for names are given in Section 3 3 If given the documentation string must be enclosed in double quotes Optional flags define the type of rule and the form of support its right hand side assertions will receive The specific flags are listed in a separate section below The LH
172. op gt name foo Find chunks that test the attribute pokey production find chunks lt x gt pokey Examples using the water jugs demo source demos water jug water jug soar production find lt s gt name lt j gt volume production find lt s gt name lt j gt volume 3 production find rhs lt j gt lt volume gt See Also sp 5 3 Configuring Trace Information and Debugging This section describes the commands used primarily for debugging or to configure the trace output printed by Soar as it runs Users may specify the content of the runtime trace output ask that they be alerted when specific productions fire and retract or request details on Soar s performance The specific commands described in this section are Summary chunk name format Specify format of the name to use for new chunks firing counts Print the number of times productions have fired pwatch Trace firings and retractions of specific productions stats Print information on Soar s runtime statistics verbose Control detailed information printed as Soar runs warnings Toggle whether or not warnings are printed watch Control the information printed as Soar runs watch wmes Print information about wmes that match a certain pat tern as they are added and removed 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 107 Of these commands watch is the most often used and the most complex pwatc
173. or remove augmentations of states that use these attribute names 2 Attribute names should not begin with a number if these attributes will be used in attribute path notation 58 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS 3 3 6 3 Removing Working Memory Elements A element is explicitly removed from working memory by following the value with a dash also called a reject gt lt s gt block lt b gt If the removal of a working memory element removes the only link between the state and working memory elements that had the value of the removed element as an iden tifier those working memory elements will be removed This is applied recursively so that all item that become unlinked are removed The reject should be used with an action that will be o supported If reject is at tempted with I support the working memory element will reappear if the reject loses I support and the element still has support 3 3 6 4 The syntax of preferences Below are the eleven types of preferences as they can appear in the actions of a production for the selection of operators RHS preferences Semantics id operator value acceptable id operator value acceptable id operator value require id operator value prohibit id operator value reject id operator value gt value2 better id operator value lt value2 worse id operator value gt best id operator value lt worst
174. or selected 2 1 a a An abstract illustration of working memory in the blocks world after the first operator has been selected 2 2 2 eee ee The six operators proposed for the initial state of the blocks world each move one block to a new location 2 2 2 ee ee The problem space in the blocks world includes all operators that move blocks from one location to another and all possible configurations of the three BIGEKS s ac ee ee he Me we Oe S E S An abstract view of production memory The productions are not related to one another s s ss be ke ee ww r A detailed illustration of Soar s decision cycle out of date A simplified version of the Soar algorithm A simplified illustration of a subgoal stack 0 A semantic net illustration of four objects in working memory An example production from the example blocks world task An example portion of the input link for the blocks world task An example portion of the output link for the blocks world task An illustration of the preference resolution process There are eight steps only five of these provide exits from the resolution process Simplified Representation of the context dependencies above the line local os upported WMEs below the line and the generation of a result In Soar 7 this situation led to non contemporaneous constraints in the chunk that generates 3 oo lt 4 24644 2 lt
175. orking memory objects At this stage of problem solving no operators have been proposed or selected not Although representing a goal explicitly has many advantages some goals are difficult to explicitly represent on the state The goal in our blocks world task is represented implicitly in the Soar program A single production rule monitors the state for completion of the goal and halts Soar when the goal is achieved 2 1 4 Proposing candidate operators As a first step in selecting an operator one or more candidate operators are proposed Operators are proposed by rules that test features of the current state When the blocks world task is run the Soar program will propose six distinct but similar operators for the initial state as illustrated in Figure 2 5 These operators correspond to the six different actions that are possible given the initial state 2 1 5 Comparing candidate operators Preferences The second step Soar takes in selecting an operator is to evaluate or compare the candidate operators In Soar this is done via rules that test the proposed operators and the current state and then create preferences Preferences assert the relative 10 CHAPTER 2 THE SOAR ARCHITECTURE links from operators to blocks are omitted for simplicity B2 B3 B2 is a block B3 is a block O4 is named move block B2 is named B B3 is named C 04
176. ormation about how the run was executed If a run was executed with the update option then then event sends a flag re questing that the environment actually update itself If a run was executed with the noupdate option then the event sends a flag requesting that the environment not update itself The update option is the default when run is specified without the self option is not specified If the self option is specified then the noupdate option is on by default It is up to the environment to check for these flags and honor them Some use cases include run self runs one agent but not the environment run self update runs one agent and the environment run runs all agents and the environment run noupdate runs all agents but not the environment Setting an interleave size When there are multiple agents running within the same process it may be useful to keep agents more closely aligned in their execution cycle than the run increment elaboration phases decisions output specifies For instance it may be necessary to keep agents in lock step at the phase level 90 eventhough the run CHAPTER 5 THE SOAR USER INTERFACE command issued is for 5 decisions Some use cases include run d 5 inteleave p run the agent one phase and then move to the next agent looping over agents until they have run for 5 de cision cycles run o 3 interleave d run the agent
177. ound Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground S3 name water jug S5 name water jug S5 desired D1 S3 desired D1 S5 operator 018 018 name pour 018 into N3 N3 volume 3 N3 contents 0 S5 jug N3 S5 problem space P3 P3 name water jug S3 jug N1 N1 volume 3 N1 contents 3 S3 jug N2 N2 volume 5 N2 contents 0 S5 jug N4 N4 volume 5 N4 contents 3 018 jug N4 soar gt explain backtraces c 21 chunk 65 d13 tie 2 Explanation of why condition chunk 65 d13 tie 2 Production chunk 64 d13 opnochange 1 matched N4 contents 3 which caused N4 contents 3 was included in production selection select failure evaluation becomes reject preference match E3 symbolic value failure which caused A result to be generated to Default Aliases Alias Maps to eb explain backtraces 124 CHAPTER 5 THE SOAR USER INTERFACE See Also save backtraces 5 4 3 indifferent selection Controls indifferent preference arbitration Synopsis indifferent selection aflr Options a ask Ask the user to choose Not implemented f first Select the first indifferent object from Soar s internal list 1l last Selec
178. p1 gt child uma and the match is possible if either lt p1 gt child oprah or lt p1 gt child uma cannot be found in working memory with the binding for lt p1 gt but not if both are present 3 3 5 9 Acceptable preferences for operators The only preferences that can appear in working memory are acceptable preferences for operators and therefore the only preferences that may appear in the conditions of a production are acceptable preferences for operators 3 3 PRODUCTION MEMORY 49 Acceptable preferences for operators can be matched in a condition by testing for a following the value This allows a production to test the existence of a candidate operator and its properties and possibly create a preference for it before it is selected In the example below operator lt o gt matches the acceptable preference for the operator augmentation of the state This does not test that operator lt o gt has been selected as the current operator sp blocks example production conditions state operator lt o gt table lt t gt lt o gt name move block gt soak In the example below the production tests the state for acceptable preferences for two different operators and also tests that these operators move different blocks sp blocks example production conditions state operator lt 01 gt lt 02 gt table lt t gt lt ol gt name move block moving block lt m1 gt
179. pe block name B lt block C gt type block name C lt table gt type table name TABLE lt ontop A gt top block lt block A gt bottom block lt table gt lt ontop B gt top block lt block B gt bottom block lt table gt lt ontop C gt top block lt block C gt bottom block lt table gt write crlf Initial state has A B and C on the table HHHHHHHEHHHHHHHHHRRAAHAA ARE HHHRRREA ARERR HHH H HAAR RHE RRS State elaborations keep track of which objects are clear There are two productions one for blocks and one for the table HHHHHHHEHHHHHHHHERHAAEAA AHHH HHH HHRA REA H EERE HAHAHAHA REHEARSE HHHHHHHHHHAE REET HHHHAAAEHA AREER HHHR REE ARR ARHA AAR Assert table always clear The conditions establish that 1 The state has a problem space named blocks 2 The state has a thing of type table The action 1 creates an acceptable preference for an attribute value pair asserting the table is clear This production will also fire once and never retract sp elaborate table clear state lt s gt problem space blocks thing lt table gt lt table gt type table gt lt table gt clear yes HHHHHHHHHHEHHHHHHHHHHHHHHEHHHHHEHHEHHEHHHHHE HEHEHE HHHEHEHH HEHEHE HHHH HEHEHE RHEE Calculate whether a block is clear The conditions establish that 1 The state has a problem space named blocks The state has a thin
180. pends upon this production instantiation and more specifically the features the instantiation tests When one of the conditions in the production instantiation no longer matches the instantiation is retracted resulting in the loss of the acceptable preference for the WME support is illustrated in Figure E 1 A copy of A in the subgoal A is retracted automatically when A 3Importantly in a technical sense the WME is only retracted when it loses instantiation support not when the creating production is retracting For example a WME could receive i support from several different instantiations and the retraction of one would not lead to the retraction of the WME However the the following generally discusses direct dependency unmediated by preferences ignoring this complication for clarity 174 APPENDIX E A GOAL DEPENDENCY SET PRIMER changes to A The substate WME persists only as long as it remains justified by A This justification is called instantiation support I support in Soar and should not be confused with result justifications In the broadest sense we can say that some feature lt b gt is dependent upon another element lt a gt if lt a gt was used in the creation of lt b gt i e if lt a gt was tested in the production instantiation that created lt b gt Further a dependent change with respect to feature lt b gt is a change to any of its instantiating features In Figure E 1 the change
181. port This appendix provides a description of when a preference is given O support by an instantiation a preference that is not given O support will have I support Soar has four possible procedures for deciding support which can be selected among with the o support mode command see page 132 However only o support modes 3 amp 4 can be considered current to Soar 8 and o support mode 4 should be considered an improved version of mode 3 The default o support mode is mode 4 In O support modes 3 amp 4 support is given production by production that is all preferences generated by the RHS of a single instantiated production will have the same support In both modes a production must meet the following two requirements to create o supported preferences 1 The RHS has no operator proposals i e nothing of the form lt s gt operator lt o gt 2 The LHS has a condition that tests the current operator i e something of the form lt s gt operator lt o gt In condition 1 the variable lt s gt must be bound to a state identifier In condition 2 the variable lt s gt must be bound to the lowest state identifier That is to say each positive condition on the LHS takes the form id attr value some of these id s match state identifiers and the system looks for the deepest matched state identifier The tested current operator must be on this state For example in the production Sometimes o support
182. put is viewed as Soar s perception and output is viewed as Soar s motor abilities When Soar interacts with an external environment it must make use of mechanisms that allow it to receive input from that environment and to effect changes in that environment the mechanisms provided in Soar are called input functions and output functions Input functions add and delete elements from working memory in response to changes in the external environment Output functions attempt to effect changes in the external environment Input is processed at the beginning of each execution cycle and output occurs at the end of each execution cycle For instructions on how to use input and output functions with Soar refer to the SML Quick Start Guide Chapter 3 The Syntax of Soar Programs This chapter describes in detail the syntax of elements in working memory preference memory and production memory and how impasses and I O are represented in working memory and in productions Working memory elements and preferences are created as Soar runs while productions are created by the user or through chunking The bulk of this chapter explains the syntax for writing productions The first section of this chapter describes the structure of working memory elements in Soar the second section describes the structure of preferences and the third section describes the structure of productions The fourth section describes the structure of impasses An overv
183. que and it will be used for all occurrences of the variable in the action side appearing in all working memory elements and preferences that are created by the production action 3 3 6 2 Creating Working Memory Elements An element is created in working memory by specifying it as an action Multiple augmentations of an object can be combined into a single action using the same syntax as in conditions including path notation and multi valued attributes gt lt s gt block color red thing lt t1 gt lt t2 gt The action above is expanded to be gt lt s gt block lt b gt lt b gt color red lt s gt thing lt t1 gt lt s gt thing lt t2 gt This will add four elements to working memory with the variables replaced with whatever values they were bound to on the condition side Since Soar is case sensitive different combinations of upper and lowercase letters represent different constants For example red Red and RED are all distinct symbols in Soar In many cases it is prudent to choose one of uppercase or lowercase and write all constants in that case to avoid confusion and bugs The constants that are used for attributes and values have a few restrictions on them 1 There are a number of architecturally created augmentations for state and im passe objects see Section 3 4 for a listing of these special augmentations User defined productions can not create
184. r such as move the red block ontop of the blue block by creating a structure on the output link such as S1 io I1 A I1 output link I3 A I3 name move block I3 moving block B1 I3 x destination 2 I3 y destination 1 B1 x location 1 B1 y location 0 B1 color red The A notation is used to indicate the working memory elements that are created by the architecture and not by productions An output function would look for specific structure in this output link and translate this into the format required by the external program that controls the robotic arm Movement by the robotic arm would lead to changes in the vision system which would later be reported on the input link Input and output are viewed from Soar s perspective An input function adds or deletes augmentations of the input link providing Soar with information about some occurrence external to Soar An output function responds to substructure of the 72 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS output link produced by production firings and causes some occurrence external to Soar Input and output occur through the io attribute of the top level state exclusively Structures placed on the input link by an input function remain there until removed by an input function During this time the structure continues to provide support for any production that has matched against it The structure does not cause the production to rematc
185. r the value of an augmentation for an object that is linked to a superstate The results produced by a single production firing are the basis for creating the actions of a chunk A new result can lead to other results by linking a superstate to a WME in the substate This WME may in turn link other WMEs in the substate to the superstate making them results Therefore the creation of a single WME that is linked to a superstate can lead to the creation of a large number of results All of the newly created results become the basis of the chunk s actions 4 2 2 Tracing the creation and reference of working memory elements Soar automatically maintains information on the creation of each working memory element in every state When a production fires a trace of the production is saved with the appropriate state A trace is a list of the working memory elements matched by the production s conditions together with the actions created by the production The appropriate state is the most recently created state i e the state lowest in the subgoal hierarchy that occurs in the production s matched working memory elements Recall that when a subgoal is created the item augmentation lists all values that lead to the impasse Chunking is complicated by the fact that the item augmentation of the substate is created by the architecture and not by productions Backtracing cannot determine the cause of these substate augmentations in the same way a
186. resent in the system With no arguments it returns a symbol whose name starts with constant With one or more arguments it takes those argument symbols concatenates them and uses that as the prefix for the new symbol It may also append a number to the resulting symbol if a symbol with that prefix as its name already exists sp gt lt s gt new symbol make constant symbol When this production fires it will create an augmentation in working memory such as S1 new symbol constant5 The production sp gt lt s gt new symbol make constant symbol lt s gt 64 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS will create an augmentation in working memory such as S1 new symbol S14 when it fires The vertical bars denote that the symbol is a constant rather than an identifier in this example the number 4 has been appended to the symbol S1 This can be particularly useful when used in conjunction with the timestamp function by using timestamp as an argument to make constant symbol you can get a new symbol that is guaranteed to be unique For example sp gt lt s gt new symbol make constant symbol timestamp When this production fires it will create an augmentation in working memory such as S1 new symbol 8 1 96 15 22 49 capitalize symbol Given a symbol this function returns a new symbol with the first character capitalized This function is pro
187. rking memory elements were matched If a matched working memory element is linked to a superstate it is included in the chunk s conditions If it is not linked to a superstate then backtracing recursively examines the trace of the production that created the working memory element Thus backtracing begins with a subgoal result traces backwards through all working memory elements that were used to produce that result and collects all of the working memory elements that are linked to a superstate This method ignores when the working memory elements were created thus allowing the conditions of one chunk to test the results of a chunk learned earlier in the subgoal The user can observe the backtracing process by setting setting backtracing on using the watch command watch backtracing on see Section 5 3 7 on page 113 This prints out a trace of the conditions as they are collected Certain productions do not participate in backtracing If a production creates only a reject preference or a desirability preference better worse indifferent or parallel then neither the preference nor the objects that led to its creation will be included in the chunk The exception to this is that if the desirability or reject preference is a result of a subgoal it will be in the chunk s actions Desirability and reject preferences should be used only as search control for choosing between legal alternatives and should not be used to guarantee the correctne
188. rn learning on in a particular problem space so that they can focus on debugging the learning problems in that particular problem space without having to address the problems elsewhere in their programs at the same time Similarly the except flag and its companion dont learn RHS action allow developers to temporarily turn learning off for debugging purposes These facilities are provided as debugging tools and do not correspond to any theory of learning in Soar The all levels and bottom up flags are orthogonal to the on except only and off flags and so may be used in combination with them With bottom up learning chunks are learned only in states in which no subgoal has yet generated a chunk In this mode chunks are learned only for the bottom of the subgoal hierarchy and not the intermediate levels With experience the subgoals at the bottom will be replaced by the chunks allowing higher level subgoals to be chunked Learning can be turned on or off at any point during a run Examples To enable learning only at the lowest subgoal level learn e b To see all the force learn and dont learn states registered by RHS actions learn 1 Default Aliases Alias Maps to l learn See Also watch explain backtraces save backtraces 5 4 5 max chunks Limit the number of chunks created during a decision cycle Synopsis max chunks n 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 127
189. rnal environment for changes The changes are reflected in an updated state description garnered from sensors Soar may also make direct changes to the state these correspond to Soar doing problem solving in its head Soar programs that do not interact with an external environment can make only direct changes to the state Internal and external problem solving should not be viewed as mutually exclusive activities in Soar Soar programs that interact with an external environment will generally have operators that make direct and indirect changes to the state The motor command is represented as substructure of the state and it is a command to the environment Also a Soar program may maintain an internal model of how it expects an external operator will modify the world if so the operator must update the internal model which is substructure of the state 12 CHAPTER 2 THE SOAR ARCHITECTURE When Soar is doing internal problem solving it must know how to modify the state descriptions appropriately when an operator is being applied If it is solving the problem in an external environment it must know what possible motor commands it can issue in order to affect its environment The example blocks world task described here does not interact with an external environment Therefore the Soar program directly makes changes to the state when operators are applied There are four changes that may need to be made when a block is moved in our task
190. rnative algorithm for determining whether a work ing memory element receives O support and configure options for selecting between mutually indifferent operators The specific commands described in this section are Summary attribute preferences mode For Soar 7 mode controls handling of preferences for non context slots explain backtraces Print information about chunk and justification backtraces indifferent selection Controls indifferent preference arbitration learn Set the parameters for chunking Soar s learning mechanism max chunks Limit the number of chunks created during a decision cycle max elaborations Limit the maximum number of elaboration cycles in a given phase max memory usage Set the number of bytes that when exceeded by an agent will trigger the memory usage exceeded event max nil output cycles Limit the maximum number of decision cycles executed without producing output multi attributes Declare multi attributes so as to increase Rete match ing efficiency numeric indifferent mode Select method for combining numeric pref erences o support mode Choose experimental variations of o support save backtraces Save trace information to explain chunks and justifi cations 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 121 set stop phase Controls the phase where agents stop when running by decision soar8 Toggle between Soar 8 methodology and Soar 7 methodology time
191. rocessing in the substate Soar s learning mechanism is called chunking it attempts to create a new production called a chunk The conditions of the chunk are the elements of the state that through some chain of production firings allowed the impasse to be resolved the action of the production is the working memory element or preference that resolved the impasse the result of the impasse The conditions and action are variablized so that this new production may match in a similar situation in the future and prevent an impasse from arising Chunks are very similar to justifications in that they are both formed via the back tracing process and both create a result in their actions However there are some important distinctions 1 Chunks are productions and are added to production memory Justifications do not appear in production memory 2 Justifications disappear as soon as the working memory element or preference they provide support for is removed 32 CHAPTER 2 THE SOAR ARCHITECTURE 3 Chunks contain variables so that they may match working memory in other situations justifications are similar to an instantiated chunk 2 8 Input and Output Many Soar users will want their programs to interact with a real or simulated envi ronment For example Soar programs may control a robot receiving sensory inputs and sending command outputs Soar programs may also interact with simulated envi ronments such as a flight simulator In
192. rol does affect the correctness of search Here are two examples 1 Some of the tests for correctness of a result are included in productions that pre fer operators that will produce correct results The system will work correctly only when those productions are loaded 2 An operator is given a worst preference indicating that it should be used only when all other options have been exhausted Because of the semantics of worst this operator will be selected after all other operators however if this operator then produces a result that is dependent on the operator occurring after all others this fact will not be captured in the conditions of the chunk In both of these cases part of the test for producing a result is implicit in search control productions This move allows the explicit state test to be simpler because any state to which the test is applied is guaranteed to satisfy some of the requirements for success However chunks created in such a problem space will be overgeneral because the implicit parts of the state test do not appear as conditions Solution To avoid this problem necessity preferences require and prohibit should be used whenever a control decision is being made that also incorporates goal attainment knowledge The necessity preferences are included in the backtrace by chunking thereby avoiding overgenerality 4 6 2 Testing for local negated conditions Overgeneral chunks can be created when negated conditions
193. rs Toggle on or off the internal timers used to profile Soar waitsnc Generate a wait state rather than a state no change impasse 5 4 1 attribute preferences mode For Soar 7 this command sets and prints the attributes preferences mode to control the handling of preferences other than acceptable and reject preferences for non context slots Synopsis attribute preferences mode 0 112 Options Handle preferences the normal Soar 6 way 1 Handle preferences the normal Soar 6 way but print a warning message whenever a preference other than or is created for a noncontext slot 2 When a preference other than or created for a non context slot print an error message and ignore discard that preference For non context slots the set of values installed in working memory is always equal to the set of acceptable values minus the set of rejected values Description For Soar 7 this command sets and prints the attributes preferences mode to control the handling of preferences other than acceptable and reject preferences for non context slots The command issued with no arguments returns the current mode This command is obsolete for Soar 8 In Soar 8 the code automatically operates as if attribute preferences mode 2 5 4 2 explain backtraces Print information about chunk and justification backtraces 122 CHAPTER 5 THE SOAR USER INTERFACE Synopsis explain backtraces f prod_name
194. rstate attribute with the value of nil the top level state has no superstate The knowledge to resolve the impasse may be retrieved by any type of problem solving from searching to discover the implications of different decisions to asking an outside agent for advice There is no a priori restriction on the processing except that it involves applying operators to states In the substate operators can be selected and applied as Soar attempts to solve the subgoal The operators proposed for solving the subgoal may be similar to the operators in the superstate or they may be entirely different While problem solving in the subgoal additional impasses may be encountered leading to new subgoals Thus it is possible for Soar to have a stack of subgoals represented as states Each state has a single superstate except the initial state and each state may have at most one substate Newly created subgoals are considered to be added to the bottom 26 CHAPTER 2 THE SOAR ARCHITECTURE state and operator superstate objects other objects Top level state operator decisions that have not yet been made acceptable preferences for operators no change attribute operator superstate choices none a iad This subgoal was created because Soar didn t know how to apply operator O2 in state S1 a Pa No operator has been r selected yet for S2 tie attribute operator superstate choices mul
195. s thus the proposal of operators is done with I supported preferences This way the operator proposals will be retracted when they no longer apply to the current situation However the actions of productions that apply an operator either by adding or removing elements from working memory need to persist even after the operator is no longer selected and operator application production instantiation no longer matches For example in placing a block on another block a condition is that the second block be clear However the action of placing the first block removes the fact that the second block is clear so the condition will no longer be satisfied Thus operator application productions do not retract their actions even if they no longer match working memory This is called O support for operator support Working memory elements that participate in the application of operators are main tained throughout the existence of the state in which the operator is applied unless explicitly removed or if they become unlinked Working memory elements are re moved by a reject action of a operator application rule Whether a working memory element receives O support or I support is determined by the structure of the production instantiation that creates the working memory element O support is given only to working memory elements created by operator application productions An operator application production tests the current operator of a
196. s gt feature 1 feature 2 feature 3 gt dont learn lt s gt The dont learn RHS action applies when learn is set to except and has no effect when other settings for learn are used force learn When learning is set to only by default chunks are not formed in any state the force learn RHS action will cause learning to be turned on for the specified state sp turn learning on state lt s gt feature 1 feature 2 feature 3 gt force learn lt s gt The force learn RHS action applies when learn is set to only and has no effect when other settings for learn are used 3 4 Impasses in Working Memory and in Produc tions When the preferences in preference memory cannot be resolved unambiguously Soar reaches an impasse as described in Section 2 6 e When Soar is unable to select a new operator in the decision cycle it is said to reach an operator impasse All impasses appear as states in working memory where they can be tested by pro ductions This section describes the structure of state objects in working memory 3 4 1 Impasses in working memory There are four types of impasses Below is a short description of the four types of impasses This was described in more detail in Section 2 6 on page 22 1 tie when there is a collection of equally eligible operators competing for the value of a particular attribute 3 4 IMPASSES IN WORKING MEMORY AND IN PRODUCTIONS 67 2 conf
197. s other working memory elements To overcome this Soar maps these augmentations onto the acceptable preferences for the operators in the item augmentations Negated conditions Negated conditions are included in a trace in the following way when a production fires its negated conditions are fully instantiated with its variables appropriate val ues This instantiation is based on the working memory elements that matched the production s positive conditions If the variable is not used in any positive conditions such as in a conjunctive negation a dummy variable is used that will later become a variable in a chunk 78 CHAPTER 4 LEARNING If the identifier used to instantiate a negated condition s identifier field is linked to the superstate then the instantiated negated condition is added to the trace as a negated condition In all other cases the negated condition is ignored because the system cannot determine why a working memory element was not produced in the subgoal and thus allowed the production to fire Ignoring these negations of conditions internal to the subgoal may lead to overgeneralization in chunking see Section 4 6 on page 80 4 2 3 Determining a chunk s conditions The conditions of a chunk are determined by a dependency analysis of production traces a process called backtracing For each instantiated production that creates a subgoal result backtracing examines the production trace to determine which wo
198. s that have a worst pref erence e Once again if the set of remaining candidates is either empty or has one member preference semantics terminates and this set is returned e Otherwise the remaining candidates are passed to the Indifferent Test IndifferentTest This operation traverses the remaining candidates and marks each candidate for which one of the following is true 170 APPENDIX D THE RESOLUTION OF OPERATOR PREFERENCES e the candidate has a unary indifferent preference e the candidate has a numeric indifferent preference e the candidate is binary indifferent to all of the remaining candidate oper ators If some candidate is left unmarked then the procedure signals a tie impasse and returns the complete set of candidates that passed into the Indifferent Test Otherwise the candidates are mutually indifferent in which case an operator is chosen according to the method set by the indifferent selection command described on page 124 Appendix E A Goal Dependency Set Primer This document briefly describes the Goal Dependency Set GDS which was intro duced with Soar 8 There are three sections a brief discussion of the motivation for the GDS a discussion of the consequences of the GDS from a behavior devel oper modeler s point of view and some details on the kernel implementation of the GDS for anyone working at the architecture level This document is by no means complete but introduces the GDS in Soar
199. se Soar Markup Language SML To learn about SML read the SML Quick Start Guide which should be located in the Documentation folder of your Soar install write This function writes its arguments to the standard output It does not automatically insert blanks linefeeds or carriage returns For example if lt o gt is bound to 4 then 3 3 PRODUCTION MEMORY 61 sp oe write lt o gt lt o gt lt o gt x lt o gt lt o gt prints 444 x4 4 crlf Short for carriage return line feed this function can be called only within write It forces a new line at its position in the write action sp gt write lt x gt crlf lt y gt 3 3 6 9 Mathematical functions The expressions described in this section can be nested to any depth For all of the functions in this section missing or non numeric arguments result in an error These symbols provide prefix notation mathematical functions These symbols work similarly to C functions They will take either integer or real number arguments The first three functions return an integer when all arguments are integers and otherwise return a real number and the last two functions always return a real number The symbol is also a unary function which given a single argument returns the product of the argument and 1 sp gt lt s gt sum lt x gt lt y gt product sum lt v gt lt w gt lt x g
200. selected 2 3 Production Memory Long term Knowledge Soar represents long term knowledge as productions that are stored in production memory illustrated in Figure 2 7 Each production has a set of conditions and a set of actions If the conditions of a production match working memory the production fires and the actions are performed 2 3 1 The structure of a production In the simplest form of a production conditions and actions refer directly to the presence or absence of objects in working memory For example a production might say CONDITIONS block A is clear block B is clear ACTIONS suggest an operator to move block A ontop of block B This is not the literal syntax of productions but a simplification The actual syntax is presented in Chapter 3 2 3 PRODUCTION MEMORY LONG TERM KNOWLEDGE 17 production name condition1 maybe some more conditions N gt S action1 Maybe some more actions C A C A C A C A C A C A C A l C A C A C A CR C A C A C A C A C A C A C A An Abstract View of Production Memory Figure 2 7 An abstract view of production memory The productions are not related to one another The conditions of a production may
201. specific terms Why the GDS was needed As a symbol system Soar attempts to approximate the knowledge level but will necessarily always fall short We can informally think of the way in which Soar falls short of the knowledge level as its peculiar psychology Those interested in using Soar to model human psychology would like Soar s psychology to approximate human psychology Those using Soar to create agent systems would like to make Soar s processing approximate the knowledge level as closely as possible However Soar 7 had a number of symbol level quirks that appeared inconsistent with human psychology and that made building large scale knowledge based systems in Soar more difficult than necessary Bob Wray s thesis 1998 addressed many of these symbol level problems in Soar among them logical inconsistency in symbol manipulations non contemporaneous constraints in chunks race conditions in rule firings and in the decision process and contention between original task knowledge and learned knowledge The Goal Dependency Set implements a solution to logical inconsistencies between persistent o supported working memory elements WMEs in a substate and its context The context consists of all the WMEs in any superstates above the local goal state In Soar any action application of an operator receives an o support 1A preliminary draft by Robert Wray contact at wrayre acm org This report will use
202. ss of the problem solving The argument is that such preferences should affect only the efficiency and not the correctness of problem solving and therefore are not necessary to produce the results Necessity preferences require or prohibit should be used to enforce the correctness of problem solving the productions that create these preferences will be included in backtracing Given that results can be created at any point during a subgoal it is possible for one result to be relevant to another result Whether or not the first result is included in the chunk for the second result depends on the links that were used to match the first result in the subgoal If the elements are linked to the superstate they are included as conditions If the elements are not linked to the superstate then the result is traced through In some cases there may be more than one set of links so it is possible for a result to be both backtraced through and included as a condition 4 3 VARIABLIZING IDENTIFIERS 79 4 3 Variablizing Identifiers Chunks are constructed by examining the traces which include working memory ele ments and operator preferences To achieve any useful generality in chunks identifiers of actual objects must be replaced by variables when the chunk is created otherwise chunks will only ever fire when the exact same objects are matched However a constant value is never variablized the actual value always appears directly in the chunk
203. st run with disks 12 See Also clog 5 0 6 Ils List the contents of the current working directory 142 CHAPTER 5 THE SOAR USER INTERFACE Synopsis ls Options No options Description List the contents of the working directory Default Aliases Alias Maps to dir ls See Also cd dirs pushd popd source 5 5 7 popd Pop the current working directory off the stack and change to the next directory on the stack Can be relative pathname or fully specified path Synopsis popd Options No options Description This command pops a directory off of the directory stack and cd s to it See the dirs command for an explanation of the directory stack 5 5 FILE SYSTEM I O COMMANDS 143 See Also cd dirs ls pushd source 5 5 8 pushd Push a directory onto the directory stack changing to it Synopsis pushd directory Options directory Directory to change to saving the current directory on to the stack Description Maintain a stack of working directories and push the directory on to the stack Can be relative path name or fully specified See Also cd dirs ls popd source 5 5 9 pwd Print the current working directory Synopsis pwd Options No options 144 CHAPTER 5 THE SOAR USER INTERFACE Description Prints the current working directory of Soar Default Aliases Alias Maps to topd pwd 5 5 10 rete net Sav
204. st the individual WME while a depth of 1 prints all WMEs which share that same identifier This is true when printing timetags identifiers or WME patterns When the depth is greater than 1 the identifier links from the specified WME s will be followed so that additional substructure is printed For example a depth of 2 means that the object specified by the identifier wme pattern or timetag will be printed along with all other objects whose identifiers appear as values of the first object This may result in multiple copies of the same object being printed out If internal is also specified then individuals WMEs and their timetags will be printed instead of the full objects Default Aliases Alias Maps to set default depth default wme depth See Also print 5 2 EXAMINING MEMORY 95 5 2 2 gds print Print the WMEs in the goal dependency set for each goal Synopsis gds print Options No options Description The Goal Dependency Set GDS is described in Appendix E This command is a debugging command for examining the GDS for each goal in the stack First it steps through all the working memory elements in the rete looking for any that are included in any goal dependency set and prints each one Then it also lists each goal in the stack and prints the wmes in the goal dependency set for that particular goal This command is useful when trying to determine why subgoals are disappearing unexpe
205. state 28 CHAPTER 2 THE SOAR ARCHITECTURE Justifications Determination of support for results Some results receive I support while others receive O support The type of support received by a result is determined by the function it plays in the superstate and not the function it played in the state in which it was created For example a result might be created through operator application in the state that created it however it might only be a state elaboration in the superstate The first function would lead to O support but the second would lead to I support In order for the architecture to determine whether a result receives I support or O support Soar must first determine the function that the working memory element or preference plays that is whether the result should be considered an operator appli cation or not To do this Soar creates a temporary production called a justification The justification summarizes the processing in the substate that led to the result The conditions of a justification are those working memory elements that exist in the superstate and above that were necessary for producing the result This is determined by collecting all of the working memory elements tested by the productions that fired in the subgoal that led to the creation of the result and then removing those conditions that test working memory elements created in the subgoal The action of the justification is the result of the subgoal
206. state of the external world add wme adds a new wme with the given id attribute value and optional preference The given id must be an existing identifier The attribute and value fields can be any Soar symbol If is given in the attribute or value field Soar creates a new identifier symbol for that field If the preference is given it can only have the value to indicate that an acceptable preference should be created for this wme Note that because the id must already exist in working memory the WME that you are adding will be attached directly or indirectly to the top level state As with other WME s any WME added via a call to add wme will automatically be removed from working memory once it is no longer attached to the top level state 5 6 SOAR I O COMMANDS 149 Examples This example adds the attribute value pair message status received to the identifier symbol S1 add wme S1 message status received This example adds an attribute value pair with an acceptable preference to the iden tifier symbol Z2 The attribute is message and the value is a unique identifier generated by Soar Note that since the is optional it has been left off in this case add wme Z2 message Default Aliases Alias Maps to aw add wme Warnings Be careful how you use this command It may have weird side effects possibly even including system crashes For example the chunker can t backtrace t
207. stifica tions and to see full wmes do any one of the following not all possibilities listed watch decisions phases productions user remove justifications remove fullwmes watch d p P f u remove j 0 watch f 1 3 u 0 j 0 Default Aliases Alias Maps to W watch See Also pwatch print run watch wmes 5 3 8 watch wmes Synopsis watch wmes alr t lt type gt pattern watch wmes 1 R t lt type gt 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 119 Options a add filter Add a filter to print wmes that meet the type and pat tern criteria r remove filter Delete filters for printing wmes that match the type and pattern criteria rls list filter List the filters of this type currently in use Does not use the pattern argument R reset filter Delete all filters of this type Does not use pattern arg t type Follow with a type of wme filter see below Pattern The pattern is an id attribute value triplet id attribute value Note that can be used in place of the id attribute or value as a wildcard that maches any string Note that braces are not used anymore Types When using the t flag it must be followed by one of the following adds Print info when a wme is added removes Print info when a wme is retracted both Print info when a wme is added or retracted When issuing a R or l the t fla
208. t lt y gt big sum lt x gt lt y gt lt z gt 402 negative x lt x gt div mod These symbols provide prefix notation binary mathematical func tions they each take two arguments These symbols work similarly to C func tions They will take only integer arguments using reals results in an error and return an integer div takes two integers and returns their integer quotient mod returns their remainder 62 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS sp gt lt s gt quotient div lt x gt lt y gt remainder mod lt x gt lt y gt abs atan2 sqrt sin cos Thesesymbols provide prefix notation unary mathematical functions they each take one argument These symbols work similarly to C functions They will take either integer or real number arguments The first function abs returns an integer when its argument is an integer and otherwise returns a real number and the last four functions always return a real number atan2 returns as a float in radians the arctangent of first_arg second_arg sin and cos take as arguments the angle in radians sp gt lt s gt abs value abs lt x gt sqrt sqrt lt x gt int Converts a single symbol to an integer constant This function expects ei ther an integer constant symbolic constant or floating point constant The symbolic constant must be a string which can be interpreted as a single inte ger The floating point co
209. t elaborate_gds is called recursively to find the context dependencies for the local contributing WME c 3 When WME changes occur each goal state must be checked to determine if the WME appeared on that goal s GDS Because WME changes occur in nearly every Soar elaboration cycle we chose to extend the WME data structure to avoid this scanning Figure E 4 illustrates the relationship Each GDS consists of a pointer to its goal and a pointer to a WME DLL list The gds_next and gds_prev pointers on WME define the GDS WMEs for a particular GDS and the GDS pointer provides a link back from each GDS WME to the GDS data structure When a WME is removed the GDS pointer can be checked to determine immediately if the goal should be removed No scanning is necessary 178 APPENDIX E A GOAL DEPENDENCY SET PRIMER PROC create_new_assertion Whenever a new o supported element is asserted the GDS is updated to include any new context dependencies Ainst lt instantiation that asserted acceptable preference for A IF A is an o supported WME G is the goal state in which A is asserted Gaps append G aps elaborate_ GDS A END PROC elaborate_GDS assertion A Se NIL FOR Each assertion c in Ainsi the instantiation supporting A D IF GoalLevel c closer to top state than GoalLevel A append c S append context dependency to GDS ELSEIF GoalLevel c same as GoalLevel A AND cis NOT an o supported WME AND c has not pr
210. t gt lt disjunction_test gt lt relational_test gt lt lt lt constant gt gt gt lt relation gt lt single_test gt Wes Beet Beets hp ey I lt variable gt lt constant gt lt lt sym_constant gt gt lt sym_constant gt lt int_constant gt lt float_constant gt gt lt gt Notes on the Condition Side e In an lt id_test gt only a lt variable gt may be used in a lt single test gt B 1 2 Grammar for Action Side Below is a grammar for the action sides of productions lt rhs gt lt rhs_action gt lt func_call gt lt func_name gt lt rhs_value gt lt attr_value_make gt lt variable_or_sym_constant gt lt value_make gt lt preference specifier gt lt unary pref gt lt unary or binary pref gt lt rhs_action gt lt variable gt lt attr_value_make gt lt func_call gt lt func_name gt lt rhs_value gt lt sym constant gt x ane lt constant gt lt func_call gt lt variable gt lt variable_or_sym_constant gt lt variable_or_sym_constant gt lt value_make gt lt variable gt lt sym_constant gt lt rhs_value gt lt preference_specifier gt lt unary preference gt lt unary or binary preference gt lt unary or binary preference gt lt rhs_value gt n wou l yn l o weu fe gt l lt l eu Appendix C The Calculation of O Sup
211. t the last indifferent object from Soar s internal list r random Select randomly default Description The indifferent selection command allows the user to set which option should be used to select between operator proposals that are mutally indifferent in preference memory The default option is random which chooses an operator at random from the set of mutually indifferent proposals with the selection biased by any existing numeric preferences For repeatable results the user may choose the first or last option First refers to the list of operator augmentations internal to Soar the ordering of the augmentations is arbitrary but deterministic so that if you run Soar repeatedly first will always make the same decision Similarly last chooses the last of the tied objects from the internal list For complete control over the decision process the ask option prompts the user to select the next operator from a list of the tied operators If no argument is provided indifferent selection will display the current setting Default Aliases Alias Maps to inds indifferent selection 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 125 See Also numeric indifference mode 5 4 4 learn Set the parameters for chunking Soar s learning mechanism Synopsis learn 1 learn dlElo learn e ab Options e enable on Turn chunking on Can be modified by
212. t time t It does not matter that A is i supported and D o supported Local I Supported Features Local i supported features are not added to the goal dependency set Instead the superstate WMEs that led to the creation of the i supported feature are determined and added to the GDS In the example when 4 is created A B and C must be added to the dependency set because they are the superstate features that led to 1 which in turn led to 2 and finally 4 However because item A was previously added to the dependency set at t4 it is unnecessary to add it again Local O Supported Features The dependencies of a local o supported feature have already been added to the state s GDS Thus tests of local o supported WMEs do not require additions to the dependency set In Figure E 2 the creation of element 5 does not change the dependency set because it is dependent only upon persistent items 3 and 4 whose features had been previously added to the GDS In Soar 8 any change to the current dependency set will cause the retraction of all subgoal structure Thus any time after time t either the D to D or A to A transition would cause the removal of the entire subgoal The E to E transition causes no retraction because E is not in the goal s dependency set 5In addition superstate WMEs can also include context slot preferences which are represented in the architecture as working memory elements 176 APPENDIX E A GOAL DEPEND
213. t valuey gt lt 1 1 gt lt gt lt y gt 10 Example Production sp propose operator to show example predicate state lt s gt car lt c gt lt c gt style convertible color lt gt rust gt lt s gt operator lt o gt lt o gt name drive car car lt c gt In this production there must be a color attribute for the working memory object that matches lt c gt and the value of that attribute must not be rust 3 3 5 4 Disjunctions of values A test for an identifier attribute or value may also be for a disjunction of constants With a disjunction there will be a match if any one of the constants is found in a working memory element and the other parts of the working memory element matches Variables and predicates may not be used within disjunctive tests Syntactically a disjunctive test is specified with double angle brackets i e lt lt and gt gt There must be spaces separating the brackets from the constants The following table provides examples of legal and illegal disjunctions Legal disjunctions Illegal disjunctions lt lt A B C 45 I17 gt gt lt lt lt A gt A gt gt lt lt 5 10 gt gt lt lt lt 5 gt 10 gt gt lt lt good morning good evening gt gt lt lt A B C gt gt Example Production For example the third condition of the following production contains a disjunction that restricts the color of
214. te If problem solving in the subgoal is contingent on quiescence having been reached the substate should test this flag The side effect is that no chunk will be built if it depended on that test See Section 4 1 on page 75 for details This attribute can be ignored when learning is turned off Knowing the names of these architecturally defined attributes and their possible val ues will help you to write productions that test for the presence of specific types of impasses so that you can attempt to resolve the impasse in a manner appropriate to your program Many of the default productions in the demos defaults directory of the Soar distribution provide means for resolving certain types of impasses You may wish to make use of some of all of these productions or merely use them as guides for writing your own set of productions to respond to impasses Examples The following is an example of a substate that is created for a tie among three operators S12 type state impasse tie choices multiple attribute operator superstate S3 item 09 010 011 quiescence t 68 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS The following is an example of a substate that is created for a no change impasse to apply an operator S12 type state impasse no change choices none attribute operator superstate S3 quiescence t S3 operator 02 3 4 2 Testing for impasses in productions Since states appear in working memory they ma
215. te with different values these are called multi valued attributes or multi attributes for short To shorten the specification of a condition tests for multi valued attributes can be shortened so that the value tests are together For example the condition 48 CHAPTER 3 THE SYNTAX OF SOAR PROGRAMS lt p1 gt type father child sally child sue could also be written as lt p1 gt type father child sally sue Multi valued attributes and variables When variables are used with multi valued attributes remember that variable bind ings are not unique unless explicitly forced to be so For example to test that an object has two values for attribute child the variables in the following condition can match to the same value lt p1 gt type father child lt c1 gt lt c2 gt To do tests for multi valued attributes with variables correctly conjunctive tests must be used as in lt p1 gt type father child lt c1 gt lt gt lt c1 gt lt c2 gt The conjunctive test lt gt lt c1 gt lt c2 gt ensures that lt c2 gt will bind to a different value than lt c1 gt binds to Negated conditions and multi valued attributes A negation can also precede an attribute with multiple values In this case it tests for the absence of the conjunction of the values For example lt p1 gt name john child oprah uma is the same as lt p1 gt name john lt p1 gt child oprah lt
216. test for the absence of a working memory element that if it existed would be local to the substate Chunking has no mechanism for determining why a given working memory element does not exist and thus a condition that occurred in a production in the subgoal is not included in the chunk For example if a production tests for the absence of a local 4 6 PROBLEMS THAT MAY ARISE WITH CHUNKING 81 flag and that flag is copied down to the substate from a superstate then the chunk should include a test that the flag in the superstate does not exist Unfortunately it is computationally expensive to determine why a given working memory element does not exist Chunking only includes negated tests if they test for the absence of superstate working memory elements Solution To avoid using negated conditions for local data the local data can be made a result by attaching it to the superstate This increases the number of chunks learned but a negated condition for the superstate can be used that leads to correct chunks 4 6 3 Testing for the substate Overgeneral chunks can be created if a result of a subgoal is dependent on the creation of an impasse within the substate For example processing in a subgoal may consist of exhaustively applying all the operators in the problem space If so then a convenient way to recognize that all operators have applied and processing is complete is to wait for a state no change impasse to occur When the impasse oc
217. the Soar agent If period is not specified this command prints the current input period If period is specified it must be a non negative integer and is used to reset the input period A period of 0 sets input to occur every elaboration cycle A positive value for period sets Soar to accept input only every nth period decision cycles The default initial setting of the input period parameter is 0 Example input period 5 Input is accepted only every 5th decision cycle by the Soar agent Soar 7 ONLY 5 7 4 srand Seed the random number generator 154 CHAPTER 5 THE SOAR USER INTERFACE Synopsis srand seed Options seed Random number generator seed Description Seeds the random number generator with the passed seed Calling srand without providing a seed will seed the generator based on the contents of dev urandom if available or else based on time and clock values Examples srand 0 5 7 5 soarnews Prints information about the current release Synopsis soarnews Default Aliases Alias Maps to sn soarnews 5 7 6 Use a default system clock timer to record the wall time required while executing a time command Synopsis time command arguments 5 7 MISCELLANEOUS 155 Options command The command to execute arguments Optional command arguments 5 7 7 unalias Undefine an existing alias Synopsis unalias
218. the match set print only the names of the produc tions that are about to fire or retract the default If printing partial matches for a production just list the partial match counts t timetags Also print the timetags of the wmes at the first failing condition w wmes Also print the full wmes not just the timetags at the first failing condition a assertions List only productions about to fire r retractions List only productions about to retract Description The matches command prints a list of productions that have instantiations in the match set i e those productions that will retract or fire in the next Propose or Apply phase It also will print partial match information for a single named production Printing the match set When printing the match set i e no production name is specified the default action prints only the names of the productions which are about to fire or retract If there are multiple instantiations of a production the total number of instantiations of that production is printed after the production name unless timetags or wmes are specified in which case each instantiation is printed on a separate line When printing the match set the assertions and retractions arguments may be specified to restrict the output to print only the assertions or retractions Printing partial matches for productions In addition to printing the current match set the m
219. then the user must run Soar by phases run p 1 Examples This example prints the productions which are about to fire and the wmes that match the productions on their left hand sides matches assertions wmes This example prints the wme timetags for a single production matches t my first production 5 2 5 memories Print memory usage for partial matches Synopsis memories cdju n memories production_name 5 2 EXAMINING MEMORY 99 Options c chunks Print memory usage of chunks d default Print memory usage of default productions j justifications Print memory usage of justifications u user Print memory usage of user defined productions production_name Print memory usage for a specific production n Number of productions to print sorted by those that use the most memory Description The memories command prints out the internal memory usage for full and partial matches of production instantiations with the productions using the most memory printed first With no arguments the memories command prints memory usage for all productions If a production_name is specified memory usage will be printed only for that production If a positive integer n is given only n productions will be printed the n productions that use the most memory Output may be restricted to print memory usage for particular types of productions using the command options Memory usage is recorded accor
220. tion When no production name is specified pwatch enable lists all produc tions currently being traced and pwatch disable disables tracing of all productions Note that pwatch now only takes one production per command Use multiple times to watch multiple functions Default Aliases Alias Maps to pw pwatch See Also watch 5 3 4 stats Print information on Soar s runtime statistics Synopsis Structured Output stats Raw Output stats s ml r Options m memory report usage for Soar s memory pools r rete report statistics about the rete structure s system report the system agent statistics This is the default if no args are specified Description This command prints Soar internal statistics The argument indicates the component of interest 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 111 With the system flag the stats command lists a summary of run statistics includ ing the following Version The Soar version number hostname and date of the run Number of productions The total number of productions loaded in the system including all chunks built during problem solving and all default productions Timing Information Might be quite detailed depending on the flags set at compile time Decision Cycles The total number of decisions in the run and the average time per decision cycle in milliseconds Elaborati
221. tional by the traced productions are printed when those productions fire or retract Watch Levels Use of the level 1 flag is optional but recommended O watch nothing equivalent to aN 1 watch decisions equivalent to d 2 watch phases and decisions equivalent to dp 3 watch productions phases and decisions equivalent to dpP 4 watch wmes productions phases and decisions equivalent to dpPw 5 watch preferences wmes productions phases and decisions equiv alent to dpPwr It is important to note that watch level 0 turns off ALL watch options including 5 3 CONFIGURING TRACE INFORMATION AND DEBUGGING 115 backtracing indifferent selection and learning However the other watch levels do not change these settings That is if any of these settings is changed from its default it will retain its new setting until it is either explicitly changed again or the watch level is set to 0 Watching Productions By default the names of the productions are printed as each production fires and retracts at watch levels 3 and higher However it may be more helpful to watch only a specific type of production The tracing of firings and retractions of productions can be limited to only certain types by the use of the following flags Option Flag Argument to Op Description tion D default remove op Control only default productions as
222. tional they fire and retract u user remove op Control only user productions as they tional fire and retract c chunks remove op Control only chunks as they fire and tional retract j justifications remove op Control only justifications as they fire tional and retract Note The pwatch command is used to watch individual productions specified by name rather than watch a type of productions such as user Additionally when watching productions users may set the level of detail to be displayed for WMEs that are added or retracted as productions fire and retract Note that detailed information about WMEs will be printed only for productions that are being watched Option Flag Argument to Option Description nN 7 nowmes No argument When watching productions do not print any information about matching wmes t timetags No argument When watching productions print only the timetags for matching wmes f fullwmes No argument When watching productions print the full matching wmes Watching Learning Option Flag Argument to Option Description L learning noprint print or fullprint Controls the printing of see table below chunks justifications as they are created 116 CHAPTER 5 THE SOAR USER INTERFACE As Soar is running it may create justifications and chunks which are added to pro duction memory The wat
223. tiple Subgoal level 2 This subgoal was created because Soar didn t know which of the three operators 04 O5 or O6 to select in state S2 Figure 2 10 A simplified illustration of a subgoal stack operator 2 6 IMPASSES AND SUBSTATES 27 of the stack the first state is therefore called the top level state See Figure 2 10 for a simplified illustrations of a subgoal stack Soar continually attempts to retrieve knowledge relevant to all goals in the subgoal stack although problem solving activity will tend to focus on the most recently cre ated state However problem solving is active at all levels and productions that match at any level will fire 2 6 3 Results In order to resolve impasses subgoals must generate results that allow the problem solving at higher levels to proceed The results of a subgoal are the working memory elements and preferences that were created in the substate and that are also linked directly or indirectly to a superstate any superstate in the stack A preference or working memory element is said to be created in a state if the production that created it tested that state and this is the most recent state that the production tested Thus if a production tests multiple states the preferences and working memory elements in its actions are considered to be created in the most recent of those states and is not considered to have been created in the other states The architecture automatically
224. to a mode where a state no change that would normally generate an impasse and subgoaling instead generates a wait state At a wait state the decision cycle will repeat and the decision cycle count is incremented but no state no change impasse and therefore no substate will be generated When issued with no arguments waitsnc returns its current setting 5 5 File System I O Commands This section describes commands which interact in one way or another with operating system input and output or file I O Users can save retrieve information to from files redirect the information printed by Soar as it runs and save and load the binary representation of productions The specific commands described in this section are Summary cd Change directory clog Record all user interface input and output to a file was log 5 5 FILE SYSTEM I O COMMANDS 137 command to file Dump the printed output and results of a command to a file dirs List the directory stack echo Print a string to the current output device Is List the contents of the current working directory popd Pop the current working directory off the stack and change to the next directory on the stack pushd Push a directory onto the directory stack changing to it pwd Print the current working directory rete net Save the current Rete net or restore a previous one set library location Set the top level directory containing demos help etc source
225. tor to elaborate an operator Mode 4 is the default Description The o support mode command is used to control the way that o support is deter mined for preferences Only o support modes 3 amp 4 can be considered current to Soar8 and o support mode 4 should be considered an improved version of mode 3 The default o support mode is mode 4 In o support modes 3 amp 4 support is given production by production that is all preferences generated by the RHS of a single instantiated production will have the same support The difference between the two modes is in how they handle pro ductions with both operator and non operator augmentations on the RHS For more information on o support calculations see the relevant appendix in the Soar manual Running o support mode with no arguments prints out the current o support mode 5 4 12 save backtraces Save trace information to explain chunks and justifications 5 4 CONFIGURING SOAR S RUNTIME PARAMETERS 133 Synopsis save backtraces ed Options e enable on Turn explain sysparam on d disable off Turn explain sysparam off Description The save backtraces variable is a toggle that controls whether or not backtracing information from chunks and justifications is saved When save backtraces is set to off backtracing information is not saved and expla nations of the chunks and justifications that are formed can not be retrieved W
226. uction s actions include preferences for new operators the production would immediately fire and create a preference for a new operator which duplicates the operator preference that was the original result of the subgoal To prevent this inhibition is used This means that each production that is built during chunking is considered to have already fired with the instantiation of the exact set of working memory elements used to create it This does not prevent a newly learned chunk from matching other working memory elements that are present and firing with those values 80 CHAPTER 4 LEARNING 4 6 Problems that May Arise with Chunking One of the weaknesses of Soar is that chunking can create overgeneral productions that apply in inappropriate situations or overspecific productions that will never fire These problems arise when chunking cannot accurately summarize the processing that led to the creation of a result Below is a description of three known problems in chunking 4 6 1 Using search control to determine correctness Overgeneral chunks can be created if a result of problem solving in a subgoal is dependent on search control knowledge Recall that desirability preferences such as better best and worst are not included in the traces of problem solving used in chunking Section 4 2 on page 76 In theory these preferences do not affect the validity of search In practice however a Soar program can be written so that search cont
227. ved and a new state is created Problem solving will now continue from this new state The impasse is not resolved and Soar does not learn in this situation The reason for regeneration is to guarantee that the working memory elements and preferences created in a substate are consistent with higher level states As stated above inconsistency can arise when a higher level state changes either as a result of changes in what is sensed in the external environment or from results produced in the subgoal The problem with inconsistency is that once inconsistency arises the problem being solved in the subgoal may no longer be the problem that actually needs to be solved Luckily not all changes to a superstate lead to inconsistency In order to detect inconsistencies Soar maintains a dependency set for every sub goal substate The dependency set consists of all working memory elements that were tested in the conditions of productions that created O supported working mem ory elements that are directly or indirectly linked to the substate Thus whenever such an O supported working memory element is created Soar records which work ing memory elements that exist in a superstate were tested directly or indirectly in creating that working memory element dependency set Whenever any of the work ing memory elements in the dependency set of a substate change the substate is regenerated Note that the creation of I supported structures in a subgoal
228. vided primarily for text output for example to allow the first word in a sentence to be capitalized capitalize symbol foo 3 3 6 11 User defined functions and interface commands as RHS actions Any function which has a certain function signature may be registered with the Kernel and called as a RHS function The function must have the following signature std string MyFunction smlRhsEventId id void pUserData Agent pAgent char const pFunctionName char const pArgument The Tcl and Java interfaces have similar function signatures Any arguments passed to the function on the RHS of a production are concatenated and passed to the function in the pArgument argument Such a function can be registered with the kernel via the client interface by calling Kernel AddRhsFunction char const pRhsFunctionName RhsEventHandler handler void pUserData The exec and cmd functions are used to call user defined functions and interface commands on the RHS of a production 3 3 PRODUCTION MEMORY 65 exec Used to call user defined registered functions Any arguments are con catenated without spaces For example if lt o gt is bound to x then sp gt exec MakeANote lt o gt 1 will call the user defined MakeANote function with the argument x1 The return value of the function if any may be placed in working memory or passed to another RHS function For example the log of a number lt x gt could be printed
229. ws sp blocks world propose move block dont do this 3 3 PRODUCTION MEMORY 53 state lt s gt problem space blocks clear block lt block1 gt clear block lt gt lt block1 gt lt block2 gt ontop top block lt blocki gt ontop bottom block lt gt lt block2 gt lt block1 gt type block gt This is not advisable because it corresponds to a different set of conditions than those in the original production the top block and bottom block need not correspond to the same ontop relation To check this we could print the original production at the Soar prompt soar gt print blocks world propose move block dont do this sp blocks world propose move block dont do this state lt s gt problem space blocks thing lt thing2 gt thing lt gt lt thing2 gt lt thing1 gt ontop lt o 1 gt ontop lt o 2 gt lt thing2 gt clear yes lt thing1 gt clear yes type block lt o 1 gt top block lt thing1 gt lt o 2 gt bottom block lt gt lt thing2 gt lt b 1 gt gt lt s gt operator lt o gt lt o gt name move block moving block lt thing1 gt destination lt thing2 gt Soar has expanded the production into the longer form and created two distinctive variables lt o 1 gt and lt o 2 gt to represent the ontop attribute These two variables will not necessarily bind to the same identifiers in working memory Negated multi va
230. y also be tested for in the conditions of productions For example the following production tests for a constraint failure impasse on the top level state sp default top goal halt operator failure Halt if no operator can be selected for the top goal default state lt s gt superstate nil state lt ss gt impasse constraint failure superstate lt s gt gt write crlf No operator can be selected for top goal write crlf Soar must halt halt 3 5 Soar I O Input and Output in Soar Many Soar users will want their programs to interact with a real or simulated envi ronment For example Soar programs could control a robot receiving sensory inputs and sending command outputs Soar programs might also interact with simulated environments such as a flight simulator The mechanisms by which Soar receives inputs and sends outputs to an external process is called Soar I O This section describes how input and output are represented in working memory and in productions The details of creating and registering the input and output functions for Soar are beyond the scope of this manual but they are described in the SML Quick Start Guide This section is provided for the sake of Soar users who will be making use of a program that has already been implemented or for those who would simply like to understand how I O is implemented in Soar 3 5 SOAR I O INPUT AND OUTPUT IN SOAR 69 3 5 1 Overview of Soar I O

The Soar User`s Manual Version 8.6.3

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