Trale Milca Environment v. 2.5.5 User`s Manual
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1. cheap ld make cpu host laptopi spawn home stefan bin trale options s c home stefan Prolog Trale Bale theory e load tsdb itsdb connect tsdb class balel threshold 2 In the options line you give a path to the grammar that should be loaded The item following class is an identifier You may have several calls to make cpu for instance if you want to use different machines or if you want to load different grammars Furthermore you have to set up the parallel virtual machine pvm Create the file pvm_hosts containing something like the following list machines accessible to PVM option fields are see pvmd 8 dx path to pvmd3 executable on remote host ep colon separated PATH used by pvmd 8 to locate executables wd working directory for remote pvmd 8 ip alternate or normalized name to use in host lookup sp VALUE Specifies the relative computational speed of this host compared to other hosts in the configuration VALUE is an inte ger in the range 1 1000000 laptopi dx home stefan Lisp lkb bin linux ep home stefan Lisp 1lkb 2003 04 15 lib linux wd tmp sp 1004 The binaries and the man pages of pvm are part of the incr TSDB dis tribution Having loaded incr TSDB you can initialize a CPU by typing 40 tsdb tsdb cpus bale Where bale is the identifier you have choosen for your CPU This should load the grammar a2. ifier then the two daughters must be coindexed The definition X X if 21 true is provided because ALE does not come with a built in equality relation defined over descriptions We leave the definitions of local_o_command 2 and o_command 2 to the reader An alternative is to formulate the constraint in the following manner BINDING THEORY PRINCIPLE A Alternate formulation spec dtr synsem content X index IndX comp dtr synsem content Y ana index IndY bot goal local_o_command X Y gt IndX IndY true X X if true The above constraint applies to any description subsumed by the antecedent If the first daughter s index locally o commands the second s then they should be coindexed Bot results in no additional description be added Alternatively one could use an anonymous variable _ Let us now see how Principle B can be written as a TRALE complex an tecedent constraint Binding Theory PRINCIPLE B spec dtr synsem content X index Ind comp dtr synsem content Y ppro index Ind gt bot goal local_o_command X Y gt fail true This constraint states that for all descriptions with specifier and complement daughters if the latter is a personal pronoun and locally o commanded by the former then the two daughters must not be coindexed Analogously Principle C can be encoded as follows BINDING THEORY PRINCIPLE C spec dtr synsem cont
3. relieving the user from having to introduce the spelling or phonology of each lexical item in the type hierarchy beforehand As another example let us see how the type hierarchy in Figure 1 1 translates into a TRALE signature As the figure shows the type agr which is immediately subsumed by L introduces three features person number and gender These features are of types per num and gen respectively The TRALE translation of this hierarchy is shown below Note that 1st 2nd and 3rd are respectively shown as first second and third because a Prolog atom has to begin with a lower case letter type_hierarchy bot per first second third num singular plural gen feminine masculine agr person per number num gender gen 1 3 2 Subtype covering TRALE assumes that subtypes exhaustively cover their supertypes i e that every object of a non maximal type t is also of one of the maximal types sub sumed by t This is only significant when the appropriateness conditions of t s maximal subtypes on the features appropriate to t do not cover the same prod ucts of values as t s appropriateness conditions Let us look at the following type hierarchy for example 1st 2nd rd singular plural feminine masculine per num gen agr PERSON per NUMBER num GENDER gen L Figure 1 1 A sample type hierarchy F F Gi Gi t F bool G bool In this hierarchy there are no t objects with identically typed
4. without the base lexicon and lexical rules but including the file generated by the lexical rule compiler For example if the grammar without the base lexicon and lexical rules is in the file theory pl and the lexical rule compiler output is in the file 1r compiler output pl one would call compiler gram theory lr compiler output 3 2 1 Input syntax The format of lexical rule specifications for the lexical rule compiler is shown in figure 3 1 Note that this syntax is different from the lexical rule syntax of ALE which also is provided by the TRALE system As described in the ALE manual lexical rules specified using the ALE lexical rule syntax result in expanding out the lexicon at compile time lex rule name input description lex rule output description gt Figure 3 1 Lexical rule input syntax A lexical rule consists of a lexical rule name followed by the infix operator followed by an input feature description followed by the infix operator lex rule followed by an output feature description and ending with a period Input and output feature descriptions are ordinary descriptions as defined in the TRALE manual The lexical compiler currently handles all kinds of descrip tions except for path inequalities Path equalities can be specified within the input or output descriptions and also between the input and output descrip tions We illustrate the syntax with the small example grammar from Meu
5. only consist of letters and numbers e g bot bool dtri New types are introduced in separate lines Each informative line must contain at least a type name A type may never occur more than once as the subtype of the same supertype It can however occur as a subtype of two or more different supertypes i e for multiple inheritance In this case it is better to add an ampersand amp to the beginning of the type name in order to prevent unintended multiple inheritance There may be zero or more features introduced for each type As mentioned before these have the form feature value All feature value pairs are sep arated by white space and they should appear in the same line Recall that feature is the name of a feature and value is the value restriction for that feature As with the types a feature name must always start with a lower case letter If a feature is specified for a type all its subtypes inherit this feature automatically As in ALE in cases of multiple inheritance the value restriction on any feature that has been inherited from the supertypes is the union of those value restrictions A single period in an otherwise blank line signals the end of a signature declaration TRALE signature specifications also allow for a_ 1 atoms as potential value restrictions As described in the ALE User s Guide the a_ 1 atoms let you use Prolog terms as featureless types For example this is useful for the value of phon features
6. or structure shared F and G values as in the following feature structures kalti Unlike ALE TRALE does not accept such undefined combinations of feature val ues as valid However if TRALE detects that only one subtype s product of values is consistent with a feature structure s product of values it will promote the product to that consistent subtype s product Thus in our example a fea ture structure t F G bool will be promoted automatically to the following Note that the type itself will not be promoted to tj A 1 3 3 Interaction with the signature e show_approp lt type gt shows the appropriateness conditions of a type e show_subtypes lt type gt shows a mini typehierarchy with the immedi ate subtypes of lt type gt e show all subtypes type shows the complete typehierarchy below type e show_supertypes lt type gt shows the immediate supertypes of type e show all supertypes type shows the hierarchy below the most general type bot and type type including only those types which are direct or indirect supertypes of type pretty funky when multiple in heritance is involved 1 4 Descriptions The following discusses some additions to the ALE description language which are included in TRALE 1 4 1 Logical variable macros TRALE s logical variable macros unlike ALE macros use logical variables in their definitions rather than true macro variables Log
7. second argument Underspecifying the first argument i e calling lex desc desc is possible to search for all lexical entries matching the description 1 6 Test sequences 1 6 1 Test files Test items are encoded as t 5 facts t Nr Test Item Desc ExpSols Comment e Nr test item ID number e Test Item test string must be enclosed in double quotes e Desc optional start category description leave uninstantiated to get all possible parses e ExpSols expected number of solutions e Comment optional comment enclosed in single quotes 1 6 2 Test queries Basic test queries e with pop up structures test Nr test From To test all e without structures testt Nr testt From To testt all 17 Testing with descriptions e with pop up structures test Nr Desc test From To Desc test all Desc e without structures testt Nr Desc testt From To Desc testt all Desc The value of Desc overrides any description given in t 5 If Desc is a variable or bot or sign all parses are returned The expected number of solutions given in t 5 is ignored 18 Chapter 2 Some examples illustrating Trale functionality This section presents some linguistic examples that take advantage of the new features in TRALE In HPSG English verbs are typically assumed to have the following two features in order to distinguish auxiliary verbs from main verbs and also to show whether a subject auxi
8. the automaton of an entry with the phonol ogy Phon one calls 1r show automaton Phon To view all such automata the predicate to call is lr show automata 0 In figure 3 7 we see the visualiza tion obtained for the lexical entry foo of our example grammar by calling show_automaton foo VCG foo automaton id1 vcg 1r tuo id2 5 lr three id3 lr one idi lr tuo id2 te QE E Ir four id4 Q8 Figure 3 7 Interaction visualization for the entry foo 3 2 2 Interpretation While the basic interpretation of lexical rules is straightforward it turns out to be more difficult to answer the question how exactly the intuition should be spelled out that properties which are not changed by the output of a lexical rule are carried over unchanged the so called framing A detailed discussion of the interpretation of lexical rules and the motivation for this particular interpreta tion can be found in Meurers 2001 we focus here on the essential ideas needed to sensibly use the lexical rule compiler A lexical rule can apply to a variety of lexical entities While each of these lexical entities must be described by the input of the lexical rule in order for the rule to apply other properties not specified by the lexical rule can and will vary between lexical entries Feature structures corresponding to lexical entities undergoing the lexical rule therefore may differ in terms of type value and ap prop
9. use one of the dot chartdisplay files supplied in trale home chart display They should be moved to chartdisplay If you put the following line in your emacs the prompt of the command go will be recognized by SICStus Prolog and you can type Ctrl C Ctrl P to get to the previous input and parse it or call it again setq sicstus prompt regexp gt gt gt MMI If your coursor is in the line of a priviously parsed utterance you may simply hit return and the sentence is parsed again 5 2 Working with the Chart Display Typing go brings you to an interactive mode You can type in a sentence and you will get parsing results displayed either with grisu or to stdout depending on whether you use grisu strongly recommended If not open the chart display will pop up after a parse and the chart will be displayed The left mouse button gives you actions you can apply to the edge you point to and the right mouse button gives you actions you can perform on the whole chart The rule names at the left hand side are also clickable Empty elements are not clickable yet 36 While in the interactive mode you can execute simple commands directly provided the command does not correspond to a lexical item in your grammar For instance reloading of a grammar can be done in the interactive mode by typing c However if your grammar contains the letter c as a lexical object it will be parsed rather than executed fs and nofs only aff
10. where n is the number of appropriate features to Type FS s value at Feat i is Val i and the appropriate value restriction of Type at Feat_i is Restr_i VisIn VisOut TagsIn and TagsOut are AVL trees They can be manipu lated using the access predicates found in the library assoc module of SIC Stus Prolog VisIn is a tree of the nodes visited so far in the current printing call and TagsIn is a tree of the nodes with re entrancies in the structure s currently being printed of which FS may just be a small piece Each node in an AVL tree has a key used for searching and a value In both Vis and Tags trees the key is a feature structure such as FS For example the call get assoc FS VisIn FSVal determines whether FS has been visited before In the Vis tree the value FSVal in the above example at a given key is not used by the default pretty printer The user may change them to anything desired When the default pretty printer adds a node to the Vis tree it adds the current FS with a fresh unbound variable as the value In the Tags tree the value at key FS is the numeric tag that the default pretty printer would print in square brackets to indicate structure sharing at that location The user may change this value using get_assoc 5 or put assoc 3 and the default pretty printer will use that with a write 1 call instead A hook must return a TagsOut and VisOut tree to the pretty printer if it succeeds At a minimum this means
11. Trale Milea Environment v 2 5 0 User s Manual Draft Gerald Penn Detmar Meurers Kordula De Kuthy Mohammad Haji Abdolhosseini Vanessa Metcalf Stevan Miller Holger Wunsch May 2003 2003 The Authors Contents 1 3 1 Signature specifications 00 1 8 0 Subtype covering cee Pode sh dike dei d d yg ee Moe ded 1 3 3 Interaction with the signature 02 1 41 Logical variable macros llle 1 4 2 Macro hierarchies ls 1 4 8 Automatic generation of macros on different types 1 5 1 Complex antecedent constraints 1 5 2 Additional commands 1 Using the Trale System 1 1 Introduction 12 Running Trale 13 Signatures 1 4 Descriptions 1 5 Theory specifications 1 6 Test sequences 1 6 4 Test files 1 6 2 Test queries Some examples illustrating Trale functionality 3 Lexical rule compiler 3 1 Introduction s sa a so t eso Rm a ms 3 2 Using the lexical rule compiler 3 21 Input syntax 9 d ds wa Powe oy dd 3 2 20 Interpretation s sn 22 2222 eee 4 Output 4 1 Savingofoutputs een A D Grisu
12. able to ALE These include re lations lexical entries lexical rules extended phrase structure rules and Prolog like definite clauses over typed feature structures They also include one extra complex antecedent constraints which is discussed in the following section 14 1 5 1 Complex antecedent constraints ALE has a restricted variety of type constraints That is to say the antecedent left hand side of these constraints can only be a type ALE constraints have the following forms t cons Desc or t cons Desc goal Goal where the antecedent t is a type and the consequent right hand side Desc is the description of the constraint These constraints apply their consequents to all feature structures of type t which is to say that they are universally quantified over all feature structures and are triggered based on subsumption i e Desc and Goal are not necessarily applied to feature structures consistent with t but rather to those that are subsumed by the most general satisfier of t as given by a constraint free signature For example the constraint a cons X g X states that the values of the F and G features of any object of type a or a type subsumed by a must not be structure shared If a goal is specified in a constraint the constraint is satisfied only if the goal succeeds TRALE generalizes this to allow for antecedents with arbitrary function free inequation free antecedents TRALE constraints are defin
13. binding TagsOut to TagsIn and VisOut to VisIn If the structure being traversed is potentially cyclic VisOut should in general update VisOut to record that the current node has been visited to avoid an infinite traversal Col is the number of columns that have already been indented before the hook was called This is useful for formatting HDIn and HDOut are hook data They are not used by the default pretty printer and are simply passed around for the convenience of hooks to record information to pass to their next invo cation The initial top level call to a portray fs hook contains 0 zero as the value of HDIn Thus HDIn can also be used to distinguish the first call from subsequent calls provided that the 0 is replaced with something else in recursive calls The file pphooks p1 discussed in subsection 7 1 3 below shows a simple printing hook to produce output very much as the default pretty printer would When a portray fs hook prints one of FS s feature values it typically will call the pretty printer rather than attempt to manipulate the data structure directly T his callback is provided by print fs VarType FS VisIn VisOut TagsIn TagsOut Col HDIn HDOut Note that the type and feature values of FS do not need to be supplied those will be filled in by the system before control is passed to portray fs or the default pretty printer 44 VarType is currently not used The other positions are the same as in port
14. bot FS2 VisMid VisOut TagsMid TagsOut NewCol HDMid HDOut 4T Bibliography Meurers W D 2001 On expressing lexical generalizations in HPSG Nordic Journal of Linguistics 24 161 127 Meurers W D and G Minnen 1997 A computational treatment of lexi cal rules in HPSG as covariation in lexical entries Computational Linguis tics 23 4 543 568 Pollard C and I Sag 1994 Head Driven Phrase Structure Grammar Studies in Contemporary Linguistics Chicago CSLI 48
15. btypes of those specified in or inferred from the lexical rule description In this way we maintain tight control over which derivations we license and we guarantee that all possible information is transferred since the appropriate feature list we use is that of a maximally specific type We create a pair of skeleton feature structures for the species pair and it is to this pair of feature structures that we add path equalities We determine the appropriate list of species pairs on the basis of the types of the input and output descriptions The first step in this process is determining the types of the input and output of the lexical rule We then obtain the list of species of the input type and the list of species of the output type We refer to these as the input species list and the output species list and their members as input and output species At this point it will be helpful to have an example to work with Consider the type hierarchy in figure 3 8 va f g h N Figure 3 8 An example hierarchy for illustrating the interpretation a C i We can couch the relationship between the input and output types in terms of type unification or in terms of species set relations In terms of unification there are four possibilities the result of unification may be the input type the output type something else or unification may fail In the first case the input type is at least as or more specific and the input spe
16. cies species will be a subset of the output species In the second case the output is more specific and the output species will be a subset of the input species In the third case the input and output types have a common subtype and the intersection of input and output species is nonempty In the fourth case the input and output types are incompatible and the intersection of their species sets is empty If a maximally specific type value can be maintained in the output it is Otherwise we map that input species to all output species In terms of set membership given a set of input species X a set of output species Y the set of species pairs P thus can be defined as 30 P a 2 ceEXALEY U x y cveX VYAyEeEY Given in figure 3 9 are examples of all four cases using the example signature p pese ee s dup type Output type E PNE e p fet T Te AENA o e f e g Ff eae XL g h 9 9 h f h g j i f i g Figure 3 9 Examples for the four cases of mappings showing input and output types the result of unification their species lists and the species pairs licensed by the algorithm described below Calling these separate cases is misleading however since the algorithm for deciding which mappings are licensed is the same in every case 31 Chapter 4 Output 4 1 Saving of outputs It can be useful to be able to save the output of a command like mgsat rec lex etc e g in order t
17. dHberfACe usu aoe oo KK mcm RR Ro ROS ee ees 4 2 1 Unfilling oT TTL 4 2 2 Feature ordering Leeds det o BE Sap ty de io eS Se o ea dodo a e 4 2 3 Diffoffeaturestructures 2 2 llle 19 23 23 23 24 29 The Chart Display 5 1 Installation and Customization 5 2 Working with the Chart Display 5 2 1 Debugging 5 22 Generation incr TSDB 6 1 Installing incr TSDB Programming hooks in Trale 7 1 Pretty printing hooks 7 1 1 Portraying feature structures 7 1 2 Portraying inequations 7 1 3 A sample pretty printing hook Chapter 1 Using the Trale System 1 1 Introduction The purpose of this manual is to provide an introduction to the features pro vided by TRALE that exist above and beyond what is provided by ALE and documented in the ALE User s Guide Some of these features exist in TRALE it self while others exist in ALE on which TRALE is implemented This manual assumes a familiarity with the ALE User s Guide TRALE is a system for parsing logic programming and constraint resolution with typed feature structures in a manner roughly consistent with their use in Head driven Phrase Structure Grammar HPSG It is written in SICStus Prolog 3 8 6 and operates by pre compiling various built ins to ALE code that are compiled fur
18. e 26 foo gt a b b minus c t2 w minus x minus y minus z hd a tl hd b tl e list bar gt a b b minus c t2 w minus x minus y minus z hd a tl e list tup gt a b b minus citi w minus x minus y minus Figure 3 5 An example set of base lexical entries 27 The user is encouraged to look at this grammar run the compiler on it and make sure that the resulting output is consistent with the user s understand ing Visualizing the lexical rule interaction generally is a good way to check whether the intended lexical rule applications do in fact result from by the lex ical rules that were specified in the grammar The visualization obtained by calling 1r_show_global 0 for the example grammar is shown in figure 3 6 VCG global fsa vcg JEE Ir_three id3 Ir four id4 X a16 Ir_three id3 Ir_one idt Ir four id4 Gi lr four id4 lr three id3 lr three id3 1r four id4 812 Ir four id4 8 lr three id3 D Iruo Ir_three id3 Ir_two id2 lr four id4 lr one idi a1 Ir four id4 a2 i add lr three id3 lr three id3 Tr eBRSS AUS a3 Ir_four id4 GIN oll 1r four id4 ed lr three id3 Figure 3 6 Global interaction visualization for the example grammar 28 The lexical rule interaction which is permitted by a particular lexical class can also be visualized To view
19. e most general and most specific at the same time i e they neither occur in other macro definitions nor are they defined in terms of other macros 11 1 4 3 Automatic generation of macros on different types Since HPSG theories usually formulate constraints about different kind of objects the grammar writer usually has to write a large number of macros to access the same attribute or to make the same specification namely one for each type of object which this macro is to apply to For example when formulating immediate dominance schemata one wants to access the VFORM specification of a sign When specifying the valence information one wants to access the VFORM specification of a synsem object And when specifying something about non local dependencies one may want to refer to VFORM specifications of local objects TRALE therefore provides a mechanism which derives definitions of macros describing one type of object on the basis of macros describing another type of object as long as the linguist tells the system which path of attributes leads from the first type of object to the second The path from one type of object to another is specified by including a declarations of the following form in the grammar access_rule type1 path type2 Such a statement is interpreted as From type1 objects you get to type2 objects by following path path Since only certain macros are supposed to undergo this extension they are specified using s
20. e portray fs 10 The source code of pphooks p1 is given below 4 pphooks pl default printer written as hook w o type or feat hiding or FS expansion portray fs Type FS KeyedFeats VisIn VisOut TagsIn TagsOut Col HDIn HDOut print Tag if shared get_assoc FS TagsIn Tag gt write write Tag write true 4 print structure if not yet visited get assoc FS VisIn VisOut VisIn TagsOut TagsIn HDOut HDIn already printed variable use Type to print var FS gt approp _ Type _ gt write mgsat write Type write write Type put assoc FS VisIn VisOut TagsOut TagsIn HDOut HDIn otherwise print Type and recurse write Type put assoc FS VisIn VisMid print feats KeyedFeats VisMid VisOut TagsIn TagsOut Col HDIn HDOut print feats Vis Vis Tags Tags Col HD HD 46 print feats fval F Val Restr Feats VisIn VisOut TagsIn TagsOut Col HDIn HDOut nl tab Col write feature F LengthF capitalise print and count 4 characters NewCol is Col LengthF 1 print fs Restr Val VisIn VisMid TagsIn TagsMid NewCol HDIn HDMid print feats Feats VisMid Vis Out TagsMid TagsOut Col HDMid HDOut portray ineq FS1 F S2 Rest Rest VisIn VisOut TagsIn TagsOut Col HDIn HDOut tab Col print fs bot FS1 VisIn VisMid TagsIn TagsMid Col HDIn HDMid nl write 7 NewCol is Col 7 print_fs
21. e present in the same directory where trale pl is located type_hierarchy bot a f bool g bool b f plus g minus c f minus g plus bool pius minus The example shows a type hierarchy with a most general element bot which immediately subsumes types a and bool Type a introduces two features F and G whose values must be of type bool Type a also subsumes two other types b and c The F feature value of the former is always plus and its G feature value is always minus The feature values of type c are the inverse of type b Finally bool has two subtypes plus and minus As shown in the example appropriate features are written after the types that introduce them The type of the value of a feature is separated from the feature by a colon as in boo1 which says the feature F takes a value of type bool Note that subtypes are written at a consistent level of increased indentation This means that if a type is introduced at column C then all its subtypes must be introduced directly below it at column C 4 n There are no requirements on the value of n other than it being consistent and greater than zero However n 2 is recommended Inconsistent indentation causes an error There can only be one type hierarchy in a signature file If more than one type hierarchy is declared in the same signature file only the first one is considered by TRALE Types are syntactically Prolog terms which means that they have to start with a lower case letter and
22. ect the feature structure output for sentences parsed in the interactive mode Parses initiated with rec directly are not affected by this switch 5 2 1 Debugging You can use the chart display for debugging rule applications First select a rule by clicking at the rule and choosing the menu item Select rule Then select an edge from the chart All goals that are at the first position of the rule specified with goal gt in the rule will be executed Then the selected edge will be unified with the first daughter of the rule If the unification succeeds and the blocked constraints that are attached to the rule and to the edge are satisfied the next goals specified in the rule will be executed If this succeeds it is checked whether there are further daughters If this is not the case we have a passive edge which is shown to the user If there are further daughters an active edge is stored This active edge can be displayed by clicking somewhere in the display and pressing the right mouse button In the following other passive edges from the chart can be combined with the active edge If the combination succeeds the rule and the successfully combined daughters are marked green Otherwise the edge that could not be combined is marked red In case of a failure another passive edge can be tested against the active edge If you select another rule the active edge is deleted The debugging of constraints that fire due to instantiations during a uni
23. ed using the infix op erator gt 2 e g f minus g plus gt X goal foo X This constraint executes foo 1 on feature structures with F value minus and G value plus These are also universally quantified and they are also triggered based on subsumption by the antecedent not unification For example in the above constraint if a feature structure does not have an F value minus and a G value plus yet but is not inconsistent with having them then TRALE will suspend consideration of the constraint until such a time as it acquires the values or becomes inconsistent with having them These constraints are thus consistent with a classical view of implication in that the inferences they witness are sound with respect to classical implication but they are not complete On the other hand they operate passively in the sense that the situation can arise in which several constraints may each be waiting for the other for their consequents to apply This is called deadlock An alternative to this approach would be to use unification to decide when to apply consequents or some built in search mechanism that would avoid deadlock but risk non termination Of the two deadlock is preferable Additional constraint logic programs can be written to search the space of possible solutions in a way suited to the individual case if there are deadlocked or suspended constraints in a solution Variables in gt constraints are implicitly existentially qua
24. ent X index Ind comp dtr synsem content Y npro index Ind gt bot goal o_command X Y gt fail true This last constraint states that for all descriptions with specifier and com plement daughters if the second one is a nonpronoun npro then it must not be o commanded by the first and coindexed with it 22 Chapter 3 Lexical rule compiler 3 1 Introduction In the framework of Head Driven Phrase Structure Grammar HPSG Pollard and Sag 1994 and other current linguistic architectures linguistic generaliza tions are often conceptualized at the lexical level Among the mechanisms for expressing such generalizations so called lexical rules are used for expressing so called horizontal generalizations cf Meurers 2001 and references cited therein Reflecting the two ways of conceptualizing lexical rules on a meta level or on the same level as the rest of the grammar the TRALE system offers two mechanisms for implementing lexical rules The meta level approach at compile time computes the transitive closure of the lexicon under lexical rule application It is described in the ALE manual The description level approach is implemented in the lexical rule compiler described in this chapter It encodes the treatment of lexical rules proposed in Meurers and Mined 1997 This chapter focuses on how to use the lexical rule compiler A discussion of this approach to lexica
25. ess suffix head h access suffix synsem s access suffix sign what a great suffix access rule synsem loc cat head head access rule sign synsem loc cat head head The result would then be 13 vform h X vform X vform s X loc cat head vform h X vformwhat a great suffix X synsem loc cat head vformh X Warnings Several kinds of warnings can appear on user output Access expansion contin ues 1 A TRALE macro already defined always has priority over a derived macro regardless of whether a the derived macro is the direct translation of an access macro defined by the user or b the derived macro is the result of access rule applications 2 If TRALE macro has already been derived by translation of an access macro with or without access rule application an access macro occurring later in the grammar which would derive the same macro is not translated an no further rules are applied to the later access macro Currently this is also the case if the two predicates differ in arity Errors Several types of errors can be detected and a message is printed on user output Access expansion then aborts 1 A type occurring in an access rule is not allowed to have a multiple suffixes defined for it b no suffixes defined for it 2 Two suffixes defined must not a be identical b have a common ending 1 5 Theory specifications TRALE theories can use all of the declarations avail
26. features This file provides the following top level predicates where lt sub super macro gt is the macro name incl its argument slots Many of the predicates exist in 10 two version one that returns single results and can be backtracked into and the other same predicate name but ending in s which returns the list of all results Note that the list returned by the second kind of predicates is sorted though Also it is worth noting that the predicates returning a list will always succeed they return a in the case where setof would fail submacro lt macro gt lt submacro gt submacros lt macro gt lt list submacros supermacro lt macro gt lt supermacro gt supermacros lt macro gt lt list supermacros gt show_submacros lt macro gt show_all_submacros lt macro gt show supermacros macro Show all supermacros macro show all macros shows the entire macro hierarchy macro lt macro gt shows the most general satisfier of the description ab breviated by the macro predicate provided by core ale pl is macro macro returns every macro that s defined if tracked back into macros list macro returns list of macros that are defined most specific macro macro most specific macros list macro most general macro macro most general macros list macro gt isolated macro macro isolated macros list macro Isolated macros are those that ar
27. fica tion is difficult To enable the debugging of single constraints a flag is set if the char tdisplay is used for debugging For instance if you want to check whether a certain constraint fires you may include debug information in the constraint In the following example the flag chart_debug 1 is tested and if its value is on a debug message is printed undelayed_accusative E1 T1 if prolog chart_debug on gt write user_error Trying to assign accusative nl user error true 333 assign acc El accusative T1 Instead of printing a message you can also call the debugger or do other things Since this constrinat may be called during the lexicon compilation as well it would be very difficult to debug without the flag since you would enter debug modus thousand times before you loaded the grammar completely 37 5 2 2 Generation Chart edges can be used as input for generation You have to specify the path in your feature structures that yields the semantic information SYNSEM LOC CONT is the predefined path The semantic contribution of a selected chart edge will be taken as input for generation and all generation results will be displayed 38 Chapter 6 lincr TSDB There is code that generates output for the profiling and test suite management tool incr TSDB developed by Stephan Oepen If you want to implement larger grammar fragments it is recommended to use this tool It provides the following fu
28. fix operator 2 indicates a logical variable macro Guard declarations for macros can optionally be applied to these parameters by appending the guard with a hyphen 3Recall that Prolog variables start with an upper case letter 4 An extensional type cannot be copied and has to be structure shared if it occurs more than once in a feature structure Extensional and intensional types are discussed in ALE User s Guide foo X a Y b f X g X h Y This declaration says that X must be consistent with type a and Y must be consistent with type b for this macro clause to apply If it does F s and G s values are shared Thus foo a b expands to the following X a g X a h b Note that ALE macros can still be declared with macro 2 As in ALE is used to call a macro in a description Let us assume that this signature is defined type_hierarchy bot person gender gen nationality nat name name gen male female nat american canadian name john mary The following macros can then be defined in the theory file man X name Y nat person name X gender male nationality Y woman X name Y nat person name X gender female nationality Y The above macros can now be called in feature descriptions using as in these lexical entries john gt man john american mary gt woman mary canadian The integrity of lexical entries can be checked by lex 1 Given the above informati
29. g meaning f will be ordered before g and at most one each of the following statements e lt lt lt h meaning h will be ordered last e gt gt gt i meaning i will be ordered first Currently only the grisu interface takes feature ordering into account but this should be added to the default textual pretty printer at some point 4 2 3 Diff of feature structures e diff NrA NrB e diff NrA PathA NrB PathB NrA and NrB are numbers of saved results PathA and PathB are paths of the form f g h i or f g h i The empty path for both cases is Output is provided via the grisu interface 34 Chapter 5 The Chart Display Trale includes code to produce output for a Chart Display developed at the DFKI in Saarbrcken The chart display has the following functionality e All passive edges that are produced during a parse are displayed e Several subsets of edges might be displayed All edges that contributed to solutions All edges that start end at a certain position All edges that were licenced by a certain rule All dominated edges of a certain edge All edges that dominate a certain edge e A list of rules in the grammar is displayed and they can be inspected e The rules can be applied interactively to edges in the chart and unification failures are displayed not fully implemented yet e You can generate from an edge not fully tested e If your grammar has an MRS semantics
30. g the latter to be equivalent to 321 I n p Izri 3o p q Here q is in the scope of the dz 3z Consequently if the genuine equivalence is desired one must ensure that zrj c do not occur in q in which case 324 3x4 p Aq and 3a1 324 p q are equivalent Requiring this extra variable hygiene is the price of permitting this non equivalent use of implication and quantification as the default rather than what is logically valid An example of such a relaxed use of such rules in linguistics is provided below spec dtr head noun index Ind head dtr head verb index Ind 16 The above constraint is formulated so as to assure subject verb agreement by enforcing structure sharing between the INDEX feature of the subject and that of the verb In the strict interpretation the second instance of the variable Ind would have broad scope existentially quantified over the entire clause and thus be possibly different from the Ind in the antecedent TRALE s interpreta tion of this however assumes they are the same As mentioned above if the strict interpretation is desired a different variable name must be used in the consequent of this constraint 1 5 2 Additional commands e lex_desc lt word gt lt desc gt shows all lexical entries having the form pro vided as first argument and compatible with the description provided as
31. g with three If you want incr TSDB to display statistics on a phenomenon based basis you have to make incr TSDB know these phenomena This can be done by specifiying them in the tsdbrc file setf phenomena append list intransitive transitive np pronoun perfect free_rc case phenomena The following should be specified in your grammar file theory pl grammar_version Trale GerGram 0 3 root_symbol root 4 symbol for input that does not end with punctuation imp symbol Oimp symbol for input that ends with decl symbol 0decl 4 symbol for input that ends with que symbol que symbol for input that ends with The grammar version will be shown in the run relation The root symbol is used for parsing The macros that are given as arguments to root symbol imp symbol decl symbol and que symbol have to be specified in your grammar The following specification can optionally be given in your theory pl before doing a parse all lexical descriptions given in retract before parsing 1 are removed this is used here to decrease the chart size zero inflected elements do not interfere retract before parsing stem 42 Chapter 7 Programming hooks in Trale 7 1 Pretty printing hooks This section is intended for more advanced audiences who are proficient in Prolog and ALE ALE uses a data structure that is not so easily readable without pre
32. ical variables entail structure sharing if used more than once in a predicate For example the Prolog expres sion foo X X means that the two arguments of foo are structure shared True macro variables on the other hand simply serve as place holders and their mul tiple occurrence does not entail structure sharing This makes a difference when a formal parameter to a macro occurs more than once in a macro definition e g foo X Y macro f X g X h Y In this ALE macro which uses true macro variables F s and G s values will not be shared in the result That is foo a b for types a and b will expand to f a g a h b in which F and G are not structure shared unless a is extensional 4 One way to make the two features values structure shared is to substitute a logical vari able as an actual parameter for X i e foo A b Note that the first argument of the macro foo here is a variable rather than an atom This variable is a logical variable because it is used as a first class citizen of ALE s description logic rather than at the macro level In this case the macro expands to the following f A g A h b TRALE s logical variable macros on the other hand automatically interpret macro parameters such as X and Y as logical variables and thus implicitly enforce structure sharing with multiple occurrences For example foo X Y X g X h Y will automatically structure share the values of F and G The in
33. ile that one compiles as usual using compile_gram 1 in order for those macros to be compiled as part of the grammar A small example Asan example say we want to have abbreviations to access the VFORM of a sign a synsem local cat and a head object Then we need to define a macro accessing the most basic object having a VFORM namely head vform_h X vform vform X Second once per grammar access suffix and access rule declarations for the grammar need to be provided The former define a naming convention for the generated macros by pairing types with macro name suffixes The latter define the rules to be used by the mechanism by specifying the relevant paths from one type of object to another access suffix head h access suffix cat c access suffix loc 1 access suffix synsem s access suffix sign what a great suffix access rule cat head head access rule loc cat cat access rule synsem loc loc access rule sign synsem synsem This results in the following macros to be generated vform h X vform X vform c X head vform h X vform l X cat vform_c X vform_s X loc vform1 X vformwhat a great suffix X synsem vform y X If we were only interested in a vform macro for certain objects say those of type sign and synsem it would suffice to specify access rules for those types instead of the access rules specified above The following specifications would do the job acc
34. l rules can be found in the Reference Manual of the Lexical Rule compiler and the original paper 3 2 Using the lexical rule compiler The lexical rule compiler is automatically loaded with the main TRALE system If the grammar contains lexical rules using the syntax described in the following section one can call the lexical rule compiler with compile_lrs lt file s gt lt outfile gt where lt files gt is either a single file or a list of files containing the part of the theory defining the base lexical entries and the lexical rules The output of the lexical rule compiler is written to the file lt outfile gt If only the first argument is provided the system writes the output to the file 1r compiler output pl After compilation the user can then access visual representations of both the global finite state automaton and the word class automata 23 The command for viewing the global automaton is 1r show global The automata for the different classes of lexical entries are shown using the command lr show automata Both commands are useful for checking that the expected sequences of lexical rule applications are actually possible for the grammar that was compiled An example is included at the end of section 3 2 1 The visualization assumes that the graph visualization tool VCG is installed on your system and in your execution path In order to parse using the output of the lexical rule compiler one must compile the grammar
35. le called theory the system provides the shortcut c The above commands automatically compile the corresponding signature file as well The name of the signature file is assumed to be signature If this is not the case it must be declared in the theory file with a signature 1 declaration For example signature foo declares the signature file associated with the theory file that contains this predicate to be foo As in ALE parsing can be performed with the rec 1 command For example to parse the sentence Kim read the book yesterday type rec kim read the book yesterday 1 8 Signatures 1 3 1 Signature specifications TRALE signatures are markedly different in format from ALE signatures When using TRALE follow the signature format discussed in this section ALE signa tures are not recognizeed by TRALE TRALE signatures are specified using a separate text file with subtyping in dicated by indentation as in the following example signature To run the bare TRALE system without the OSU extensions and graphical user interface set your TRALE HOME environment variable to the location where TRALE lives After starting SICStus Prolog type compile lt trale_dir gt trale where lt trale_dir gt is the location of trale pl This command loads and compiles TRALE which in turn loads and compiles parts of ALE code that are necessary for its operation A copy of ale pl thus must also b
36. liary inversion has taken place verb AUX bool INV bool The values for the AUX and INV features are taken to be of type bool However note that there cannot be any verbal type with the following combination of feature values AUX INV That is there are no verbs in English that can occur before the subject and not be auxiliaries Thus using TRALE s interpretation of sub typing we can prevent this undesirable combination with the following type hierarchy type_hierarchy bot bool plus minus verb aux bool inv bool aux_verb aux plus inv bool main_verb aux minus inv minus 19 Whenever there is an object of type main_verb its AUX and INV feature values must be set to minus In the case of auxiliaries their AUX feature has to be plus but their INV feature could be either plus or minus The following example shows a TRALE logical variable macro This macro assumes subject verb agreement holds vp Ind synsem local content index Ind cat subcat synsem local content index Ind ja As mentioned in subsection 1 4 1 TRALE treats variables used in TRALE macro defini tions as logical variables and therefore assumes structure sharing between multiple occurrences of such variables Using a TRALE logical variable macro we ensure that the values of the INDEX feature of the verb phrase and of the subject are structure shared Therefore vp person third number singular is equivalent to synsem l
37. lightly different operators than standard TRALE macros access macros are specified using the instead of the operator of ordinary macros The type of the macro is determined on the basis of the access suffix The typing of each of the arguments if any is added using the operator after each argument To distinguish the macro names for different type of objects a naming con vention for macros is needed All macros on objects of a certain type therefore have the same suffix e g s for all macros describing signs The type suffix pairing chosen by the linguist is specified by including declarations of the fol lowing form in the grammar access suffix type suffix Such a statement declares that the names of macros describing objects of type type end in suffix So the extend access mechanism reduces the work of the linguist to providing e macros describing the most basic type of object and e access suffix and access rule declarations Access macros are not compiled directly Instead the access macros must be translated to ordinary TRALE macros at some point before compiling a grammar using a call to extend_access lt FileList gt lt QutFileName gt where lt FileList gt is a Prolog list of Filenames containing access macro declarations 12 and lt OutFileName gt is a single file containing the ordinary TRALE macros Note that this resulting file needs to be explicitly loaded as part of the theory f
38. nctionality and much more e storing time number of passive edges memory requirements errors for every parsed item e compare test runs performance coverage overgeneration e detailed comparison on item basis of number of readings edges the derivations i e tree structure with rule names the MRSes e test parts of test suites on a phenomenon basis or some other selection from your test items restrictions may be formulated in SQL queries The incr TSDB uses the Parallel Virtual Machine If you have several CPUs idle you may distribute the processing of your test suite over several machines which enormously shortens the time needed for testing and speeds up grammar development 6 1 Installing incr TSDB Get the itsdb package from http lingo stanford edu ftp and install it How to do this is described in the documentation which can be found also at this site Set the SICStus path For instance if you use tcsh put the following in your teshre 39 setenv SP PATH usr local lib sicstus 3 9 1 incr TSDB is called via foreign functions The file is linked to libitsdb so which has to be in the LD_LIBRARY_PATH Put something like the following in your tcshrc or the respective file for the shell you are using setenv LD LIBRARY PATH home stefan Lisp lkb lib linux Create a file tsdbrc to include something like the following setf pvm cpus list academic
39. nd come back saying something like wait for clients laptop1 registered as tid 262179 After successful registration of a client i e after loading your grammar and after the creation of a test suite with the incr TSDB podium you can process items for instance by using Process All Items in the incr TSDB podium Please refer to the incr TSDB manual and further documentation You can put together your own test suite by using the incr TSDB import function File Import Test Items This function imports data from an ASCII text file For example intransitive Karl schlft Der Mann schlft transitive Liebt Karl Maria Karl liebt Maria 333 Dp der Mann der klug Mann der Mann der ihn kennt pronoun Er schlft Er kennt ihn subjless Mich drstet particle verbs Karl denkt nach Karl denkt ber Maria nach Karl nachdenkt ber Maria unaccusatives Er fllt mir auf perfect Er hat geschlafen Du wirst schlafen Du wirst geschlafen haben free rc Wer schlft stirbt Wen ich kenne begre ich Was er kennt it er Wo ich arbeite schlafe ich ber was ich nachdenke hast du nachgedacht 41 for a description of example sessions Ich liebe ber was du nachdenkst ber was du nachdenkst gefllt mir 333 case Liebt ihn ihn Ungrammatical sentences are marked with a star The phenomenon is given on a separate line startin
40. ntified within the antecedent Thus 15 f X g X gt Y goal foo Y applies the consequent when F s and G s values are structure shared In other words it applies the consequent if there exists an X such that F s and G s values are both X In addition the consequent of the above mentioned constraint im plicitly applies only to feature structures for which F and G are both appropriate Path equations can be used in antecedents to explicitly request structure sharing as well The following constraint is equivalent to the one above f g Y goal foo Y A singleton variable in the antecedent results in no delaying itself apart from the implicit appropriateness conditions Variables occurring in the consequent are in fact bound with scope that extends over the consequent and relational attachments Thus in the following example f X g X gt W goal foo X W the first argument passed to foo 2 is the very X that is the value of both F and G This use of variables on both sides of the implication is a loose interpretation consistent with common practice in linguistics With a classical interpretation of implication it is always true that pq iff p p q Thus 321 9z4 p gt q iff Gar 4dan p Aa1 4a n p Aq Note that according to the classical interpretation q is not in the scope of the existential quantifiers TRALE however bends this rule takin
41. o e output it again without reperforming the actual task e view it pretty printed using different pretty printers e g grisu or text e run a diff of the two structures see below e save results on saves copies of the output for later use during the same sesssion e save results off switches saving results off What was saved is pre served e show saved nr shows saved result number jnrj e show all saved shows all saved results e saved id nr returns number of saved results e save results filename save results in a file e load_results lt filename gt loads results from a file At system startup saving of results is off 4 2 Grisu interface The Grisu interface developed by Holger Wunsch and Detmar Meurers is a stan dalone program written in C based on the freely available Qt www trolltech com and KDE libraries www kde org By starting trale with the g option the Grisu 32 interface is automatically started and used to display trees and attribute value matrices AVMs Grisu can also produce Latex output of trees and AVMs The Grisu interface is described in a separate manual that is included in its distribution In this section we describe Trale options and features that are available when using the Grisu interface e General switches grisu_off switches grisu output off and textual pretty printer on grisu_on switches grisu output on if the system had been
42. ocal content index Ind person third number singular cat subcat synsem local content index Ind In the above feature structure the values of both INDEX features are structure shared Had we used a regular ALE macro using macro 1 we would have reached a similar result but the values of the INDEX features would simply have been structure identical We can also use the type guard declaration of TRALE macros to make sure that Ind is consistent with the type ind This can be achieved by adding the guard to the head of the macro definition as follows vp Ind ind synsem local content index Ind cat subcat synsem local content index Ind In some languages the form of the verb depends on the type of eventuality denoted by the sentence In Czech for example it is generally the case that if an event is total i e completed as opposed to simply terminated the verb that denotes that event surfaces in the perfective form This rule can be enforced as the following constraint in the grammar Note that since the constraint applies to a type rather than a particular description we could use an ALE constraint cons 2 too sentence event total gt synsem local cat head vform perf 20 This constraint applies its consequent to all feature structures of type sentence with the required EVENT value Another example of a complex antecedent constraint can be found in HPSG s Binding Theory which refers to the n
43. on for example lex john results in the following output in TRALE lex john WORD john ENTRY person GENDER male NAME john NATIONALITY american ANOTHER n yes In addition one may check the integrity of macro definitions by macro 1 In this case macro woman X Y produces the following output macro woman X Y MACRO woman 0 name 1 nat ABBREVIATES person GENDER female NAME 0 NATIONALITY 1 ANOTHER n yes 1 4 2 Macro hierarchies Macros can be hierarchically organized by calling one macro in the definition of another The macro X occuring in the definition of a macro Y then can be referred to as a supermacro of X And conversely Y is a submacro of macro X The notions of sub and supermacro thus in one sense are parallel to the notion of sub and supertype But it is important to keep in mind that onto logically macros and types are very different in particular an object of a type will also be of one of its subtypes and of exactly one of its most specific sub types There is no equivalent to this with macro hierarchies which are just subsumption hierarchies of some descriptions that were given names Different from types macros have no theoretical status they just serve to write down a theory more compactly In terms of the macro hiearchy comands below note note that parallel to types the sub and supermacro relations only include macros on the same level not those embedded under
44. otions of o binding and o commanding O binding is defined as follows see Pollard and Sag 1994 p 253 54 Y locally o binds Z just in case Y and Z are coindexed and Y locally o commands Z If Z is not locally o bound then it is said to be locally o free Pollard and Sag define o commanding as follows Let Y and Z be synsem objects with distinct LOCAL values Y referential Then Y locally o commands Z just in case Y is less oblique than Z Let Y and Z be synsem objects with distinct LOCAL values Y ref erential Then Y o commands Z just in case Y locally o commands X dominating Z Based on these notions HPSG s Binding Theory is phrased as the following three principles ibid HPSG Binding Theory Principle A A locally o commanded anaphor must be locally o bound Principle B A personal pronoun must be locally o free Principle C A nonpronoun must be o free A simplified version of Principle A can be written as a constraint over all head comple ment structures head comp struc as follows BINDING THEORY PRINCIPLE A head comp struc gt spec dtr synsem content X index IndX comp dtr synsem content Y ana index IndY goal local_o_command X Y gt IndX IndY true X X if true The above ALE constraint makes sure that for all head comp struc type objects if the complement daughter is anaphoric and locally o commanded by the spec
45. ray fs 7 1 2 Portraying inequations The hook for inequations is portray_ineq FS1 FS2 IqsIn IqsOut TagsIn TagsOut VisIn VisOut Col HDIn HDOut This is called when there is an inequation between FS1 and FS2 with IqsIn being the remaining inequations The hook should return the remainder to consider printing next in IqsOut which is normally bound to IqsIn IqsIn can also be used to test whether FS1 FS2 is the last inequation Col is the number of columns that the default pretty printer would print before printing FS1 This is different from the use of Col in potray fs where it is the number of columns already printed The other arguments are the same as in portray fs Inequations are typically printed after all feature structures and their sub structures in a top level call to the pretty printer have been printed Likewise portray ineq is only called once portray_fs has been called on all feature structures and their substructures in a top level call Typically the arguments to inequations will thus have been visited before the only exceptions to this are inequated extensionally typed feature structures 7 1 3 A sample pretty printing hook The following Prolog code shows how the default pretty printer can be written as a hook This code is available online on the ALE web site under the name pphooks pl The file has two top level predicates portray_fs 10 and portray ineq 11 As mentioned above the former is responsible for p
46. rers and Minnen 1997 which is also included with the TRALE system in the subdirectory lr compiler examples The signature of this example is shown in figure 3 2 to illustrate this TRALE signature syntax figure 3 3 shows the type hierarchy in the common graphical notation Based on this signature figure 3 4 shows a set of four lexical rules exempli fying the lexical rule syntax used as input to the lexical rule compiler To complete the example grammar we include three examples for base lexical entries in figure 3 5 These lexical entries can be found in the file lexicon pl I The tool is freely available from http rwu4 cs uni sb de users sander html gsvcgi html 24 type_hierarchy bot t w bool x bool y bool ti t2 z list word a val b bool c t list bool val list e_list ne_list hd val tl list bool plus minus val a b Figure 3 2 An example signature i enc val TS N t1 t2 elist nelist plus minus a b Figure 3 3 A graphical representation of the example type hierarchy 25 lr_one b minus c y minus lex_rule a b c x plus y plus lr two a b b minus c w minus lex rule c w plus lr three c t2 w plus x plus z t1 QOne lex_rule c y plus z ne lr four b minus c t2 w plus x plus z e_list lex_rule b plus c x minus Figure 3 4 An example set of four lexical rul
47. riate features Frames carrying over properties not changed by the lexical rule need to take into account different feature geometries Since framing uti lizes structure sharing between input and output we only need to be concerned with the different kinds of objects that can undergo a lexical rule with regard to the paths and subpaths mentioned in the output description Specifically when the objects undergoing lexical rule application differ with regard to type value along some path mentioned in the output description we may need to take into account additional appropriate attributes in framing Each such possibility will demand its own frame The lexical rule compiler provides a truthful procedural realization of the for mal interpretation of lexical rules defined in Meurers 2001 Generally speaking the input description of a lexical rule specifies enough information to capture 29 the class of lexical entries intended by the user to serve as inputs The output description on the other hand specifies what should change in the derivation All other specifications of the input are supposed to stay the same in the output In the spirit of preserving as much information as possible from input to output we generate frames on the basis of species most specific type pairs that is we generate a frame an IN OUT pair on the basis of a maximally specific input type and a maximally specific output type su
48. rinting feature structures and the latter for printing inequations The first thing that portray_fs 10 does is check whether the feature struc ture it is printing is tagged i e whether it is structure shared with another fea ture structure This check is made using get_assoc FS TagsIn Tag If so the tag is printed between square brackets Then using get assoc FS VisIn the system determines whether the feature structure has already been printed Should this be the case VisOut TagsOut and HDOut are respectively bound with VisIn TagsIn and HDIn and the hook succeeds with nothing else printed If on the other hand the feature structure has not been printed already and FS is a variable then either Type or in case Type has at least one appro priate feature mgsat Type is printed Then put assoc 4 is used to update VisOut to include FS and TagsOut and HDOut are bound to TagsIn and HDIn respectively In case the feature structure is not a variable its type is written and a call to a recursive predicate is made to print each feature value pair of FS in turn 45 Two important things to note are that 1 VisOut is updated to include FS before the call is made to avoid non termination on cyclic structures and 2 the feature values are actually printed with a callback to print_fs 9 which in turn calls portray_fs 10 again The predicate portray ineq 11 works similarly Note that Col spaces are added by the hook itself unlik
49. started with grisu grisu_debug sends the output normally sent to grisu to standard out instead grisu_nodebug reverts to sending grisu output to the socket at which grisu listsns At system startup grisu is on if trale has been started with g e Tree vs AVM output pref_struc_on switches grisu to show new data in the form of an AVM pref_struc_off switches grisu to show new data in the form of a tree if one exists in the data package At system startup the setting is pref struc off Note that both options only determine what is shown first in Grisu one can select to show either representation 4 2 1 Unfilling When running a grammar with a large signature e g MERGE you ll imme diately notice how essential proper unfilling of uninformative features is The code now assumes a node to be informative if a it is of a type that is more specific than the appropriave value of the feature that led to it For the top level the appropriate value is taken to be bot or b it is structure shared with some other node or c the value of one of its features is informative according to a b or c e unfill_on switches on unfilling of uninformative nodes in the output e unfill off switches it off At system startup unfill is on 33 4 2 2 Feature ordering To specify the order in which features are displayed by the pretty printer include any number of statements of the form e f lt lt lt
50. ther to Prolog code by ALE and ultimately to lower level code by the SICStus compiler TRALE has all of the functionality of ALE plus some extras which are explained in the following sections The most apparent differ ence between ALE and TRALE is the signature specifications This is discussed in section 1 3 Section 1 5 talks about an extra feature regarding theory specifica tions In chapter 2 some linguistic examples that make use of the new features of TRALE are presented The last section discusses the pretty printing hooks that have been introduced in ALE We start out with an overview on how to run TRALE and get started 1 2 Running Trale To run the TRALE Milca release call trale or trale g to start it with the graphical user interface Grisu Calling trale h returns a list of other options lALE User s Guide is available online at http www cs toronto edu gpenn ale html which are available Two files are necessary to declare a TRALE grammar a signature file which defines type hierarchies and a theory file which defines lexical items phrase structure rules relations etc relative to the signature defined in the signature file These files are discussed in more detail below To load and compile a theory and its corresponding signature file type compile gram theory file where theory file is the name of the theory file As a shortcut for the compilation of a fi
51. tty printing or access predicates In order to make pretty printing more customiz able hooks are provided to portray feature structures and inequations If these hooks succeed the pretty printer assumes that the structure inequation has been printed and quietly succeeds If the hooks fail the pretty printer will print the structure inequation by the default method used in previous versions of ALE The hooks are called with every pretty printing call to a substructure of a given feature structure It is therefore important that the user s hooks use the arguments provided to mark visited substructures if the feature structure being printed is potentially cyclic or else pretty printing may not terminate 7 1 1 Portraying feature structures The hook for portraying feature structures is portray fs Type FS KeyedFeats VisIn VisOut TagsIn TagsOut Col HDIn HDOut FS is the feature structure to be printed This is ALE s internal representation of this structure It is recommended that access to information in this structure be obtained by Type and KeyedFeats although the brave of heart may wish to work with it directly FS is also used to check token identity with structures in the Vis and Tags trees as described below Type is the type of FS KeyedFeats is a list of fval 3 triples 1The reader is referred to the ALE User s Guide for the structure of this representation 43 fval Feat_1 Val_1 Restr_1 fval Feat n Val n Restr n
52. you can display MRSses 5 1 Installation and Customization To get the Tcl TK code please contact Stephan Busemann Stephan Busemann dfki de The TCL TK code has to be installed in the trale directory under chart display TCL Tcl TK has to be installed and wish has to be in your search path Specify the following in your theory pl 7 load cd 4 loads the code for the chart display 35 root symbol 6root symbol for input that does not end with punctuation imp_symbol imp symbol for input that ends with decl_symbol dec1 symbol for input that ends with que_symbol que symbol for input that ends with cont_path synsem loc cont the path to the semantic content chart display switches the chart display on default nochart display 4 switches the chart display off english 4 the commands in the Chartdisplay are English default german 4 the commands in the Chartdisplay are German tcl warnings output of warnings in a TCL window default notcl warnings output of warnings to console mrs output of MRS for a parsed string nomrs 4 no output default fs switches feature structure output on default nofs 4 switches feature structure output off The macros that are given as arguments to root symbol imp symbol decl symbol and que symbol have to be specified in your grammar You may customize the chart display yourself or
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