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RACER User's Guide and Reference Manual Version 1.6

1. G TBN concept term TBox name List of name sets This macro return the transitive closure of the macro concept children atomic concept descendants function Description Syntax Arguments Values Remarks Gets all atomic concepts of a TBox which are subsumed by the specified concept atomic concept descendants C thor C tbox concept term TBox object List of name sets Returns the transitive closure from the call of atomic concept children 47 concept ancestors KRSS macro Description Syntax Arguments Values Remarks Gets all atomic concepts of a TBox which are subsuming the specified con cept concept ancestors C koptional TBN tbox name current tbox C concept term TBN TBox name List of name sets This macro return the transitive closure of the macro concept parents atomic concept ancestors function Description Syntax Arguments Values Remarks Gets all atomic concepts of a TBox which are subsuming the specified con cept atomic concept ancestors C tbox C concept term tbor TBox object List of name sets Returns the transitive closure from the call of atomic concept parents concept children KRSS macro Description Syntax Arguments Values Remarks Gets the direct subsumees of the specified concept in the TBox concept children C amp optional TBN tbox name
2. atomic role inverse function Description Returns the inverse role of role term R Syntax atomic role inverse R thor Arguments R role term tbox TBox object Values Role name or term for the inverse role of R 39 role inverse macro Description Syntax Arguments Values Remarks Returns the inverse role of role term R role inverse R amp optional TBN tbox name current tbox R role term TBN TBox name Role name or term for the inverse role of R This macro uses atomic role inverse 7 3 TBox Evaluation Functions classify tbox Junction Description Classifies the whole TBox Syntax classify tbox amp optional tbor current tbox Arguments thor TBox object Remarks This function needs to be executed before gueries can be posed check tbox coherence function Description This function checks if there are any unsatisfiable atomic concepts in the given TBox Syntax check tbox coherence amp optional tbor current tbox Arguments thor TBox object Values Returns a list of all atomic concepts in tbox that are not satisfiable i e an empty list NIL indicates that there is no additional synonym to bottom Remarks This function does not compute the concept hierarchy It is much faster than classify tbox so whenever it is sufficient for your application use check tbox coherence This function is supplied in order to check whether an atomic concept is sat
3. at most n R exactly n R at least n R C at most n R C exactly n R C gt aexpr aexpr gt aexpr aexpr lt aexpr aexpr lt aexpr aexpr aexpr aexpr min AN integer max AN integer R RN inv RN Figure 4 RACER concept and role terms for the attribute expressions aexpr see below DL notation RACER syntax At most restriction lt nR at most n R At least restriction gt nR at least n R Exactly restriction n R exactly n R Qualified at most restriction lt n R C at most n R C Qualified at least restriction gt n R C at least n R C Qualified exactly restriction n R C exactly n R C Actually the exactly restriction exactly n R is an abbreviation for the concept term and at least n R at most n R and exactly n R C is an abbreviation for the concept term and at least n R C at most n R C There are two concepts implicitly declared in every TBox the concept top T denotes the top most concept in the hierarchy and the concept bottom L denotes the inconsistent concept which is a subconcept to all other concepts Note that T L can also be expressed as C U C C N C In RACER T is denoted as top and is denoted as bottom 3For KRSS compatibility reasons RACER also supports the synonym concepts top and bottom aezpr AN real aexpri aexpr1 aexprl aexprl real AN real AN Figure 5 Attribute expressions 3 2 Conce
4. function Description Syntax Arguments Values Remarks Generates a new TBox or initializes an existing TBox and binds it to the vari able current tbox During the initialization all user defined concept ax ioms and role declarations are deleted only the concepts top and bottom remain in the TBox init tbox thor amp optional class tbox tbox TBox object class class inheriting from the class tbox tbox This is the way to create a new TBox object 14 signature macro Description Defines the signature for a knowledge base If the keywords atomic concepts and roles are used The current tbox is initial ized and the signature is defined for it If the keyword individualnames is used the current abox is initialized If all key words are used the current abox and its TBox are both initialized Syntax signature amp key atomic concepts nil roles nil individuals nil Arguments atomic concepts is a list of all the concept names specifying C roles is a list of all role declarations thereby also specifying R individuals is a list of individual names specifying Z Remarks Usually this macro is used at top of a file directly after the macro in knowledge base in tbox or in abox Actually it is not necessary in RACER to specify the signature but it helps to avoid errors due to typos Examples Signature for a TBox signature atomic concepts Chara
5. class standard abox Arguments abor ABox object to initialize tbox TBox object associated with the ABox class class of the new ABox object that must inherit from the class standard abox Values ABox object Remarks The tbox has to already exist before it can be referred to by init abox ensure abox signature function Description Defines the signature for an ABox and initializes the ABox Syntax ensure abox signature abor amp key individuals nil Arguments abor ABox object individuals is a list of individual names specifying ZT See also Macro signature on page 14 is the macro counterpart It allows to specify a signature for an ABox and a TBox with one call 18 in knowledge base macro Description This form is an abbreviation for the sequence in tbox TBN in abox ABN TBN Syntax in knowledge base TBN ABN amp optional name cl user Arguments TBN TBox name ABN ABox name name Package name Examples in knowledge base peanuts peanuts characters current abox special variable Description The variable current abox refers to the current ABox object It is set by the function init abox or by the macros in abox and in knwoledge base 19 save abox function Description If a pathname is specified an ABox is saved to a file In case a stream is specified the ABox is written to the stream the stream must already be open and the keywords if exists and if does
6. 335 Loading racer examples family abox lisp T sue some ABox queries 333 Is Doris a woman CL USER 7 individual instance doris woman T 335 Of which concepts is Eve an instance CL USER 8 individual types eve SISTER WOMAN PERSON HUMAN TOP TOP 333 get all direct types of eve CL USER 9 individual direct types eve SISTER 333 get all descendants of Alice CL USER 10 individual fillers alice has descendant DORIS EVE CHARLES BETTY 333 get all instances of the concept sister CL USER 11 concept instances sister DORIS BETTY EVE In the Appendix different versions of this knowledge base can be found In Appendix A on page 62 you find a version in KRSS syntax and in Appendix B on page 63 a version where the TBox and ABox are integrated 2 3 Naming Conventions Throughout this document we use the following abbreviations possibly subscripted C Concept term name Name of any sort CN Concept name S List of Assertions IN Individual name GNL List of group names IN Object name LCN List of concept names R Role term abor ABox object RN Role name tbor TBox object AN Attribute name n A natural number ABN ABox name real A real number TBN TBox name integer An integer number All names are Lisp symbols the concepts are symbols or lists Please note that for macros in contrast to functions the arguments should not be quoted The API is designed to the following conventions For most of the services o
7. 44 concept 33 conjunction of roles 9 define concept 22 define disjoint primitive concept 22 define distinct individual 29 define primitive attribute 25 define primitive concept 21 define primitive role 24 delete ABox 18 delete TBox 14 describe abox 59 describe concept 52 describe individual 59 describe role 52 describe tbox 51 disjoint 21 disjoint concepts 8 21 22 domain restriction 9 ensure abox signature 16 ensure tbox signature 13 equivalent 21 exists restriction 7 feature 8 23 25 feature p 36 feature 36 find abox 18 find tbox 15 forget 30 forget concept assertion 27 forget role assertion 29 GCI 7 20 implies 20 in abox 15 in knowledge base 17 in tbox 12 individual direct types 52 individual equal 43 individual fillers 54 individual instance p 42 individual instance 41 individual not egual 43 individual p 43 individual types 53 individual 43 individuals related p 42 individuals related 42 inference modes 10 init abox 16 init tbox 12 instance 27 instantiators 53 load ABox 17 load TBox 14 loop over aboxes 56 loop over tboxes 50 most specific instantiators 53 name set 44 number restriction 7 primitive concept 8 67 range restriction 9 realize abox 40 reflexive p 37 reflexive 37 related 28 related individuals 55 rename ABox 18 rename TBox 14 retraction 11 retrieve concept instances 54
8. Arguments R role term tbox TBox object Values Returns t if the role R is a feature in tbox and nil otherwise feature macro Description Checks if R is a feature in the specified TBox Syntax feature R optional TBN tbox name current tbox Arguments R role term TBN TBox name Values Returns t if the role R is a feature in TBN and nil otherwise symmetric p function Description Checks if R is symmetric in the specified TBox Syntax symmetric p R amp optional tbox current tbox Arguments R role term tbox TBox object Values Returns t if the role R is symmetric in thor and nil otherwise 38 symmetric macro Description Checks if R is symmetric in the specified TBox Syntax symmetric R amp optional TBN tbox name current tbox Arguments R role term TBN TBox name Values Returns t if the role R is symmetric in TBN and nil otherwise reflexive p function Description Checks if R is reflexive in the specified TBox Syntax reflexive p R amp optional tbox current tbox Arguments R role term tbox TBox object Values Returns t if the role R is reflexive in tbox and nil otherwise reflexive macro Description Checks if R is reflexive in the specified TBox Syntax reflexive R amp optional TBN tbox name current tbox Arguments R role term TBN TBox name Values Returns t if the role is reflexive in TBN and nil otherwise
9. Description Checks if the ABox is consistent Syntax abox consistent optional ABN abox name current abox Arguments ABN ABox name Values Returns t if the ABox ABN is consistent and nil otherwise Remarks This macro uses abox consistent p check abox coherence function Description Checks if the ABox is consistent If there is a contradiction this function prints information about the culprits Syntax check abox coherence optional abor current abox stream standard output Arguments abor ABox object stream Stream object Values Returns t if abox is consistent and nil otherwise individual instance KRSS macro Description Checks if an individual is an instance of a given concept with respect to the current abox and its TBox Syntax individual instance IN C optional abor abox name current abox Arguments IN individual name C concept term abor ABox object Values Returns t if IN is an instance of C in abox and nil otherwise 43 individual instance p function Description Syntax Arguments Values Checks if an individual is an instance of a given concept with respect to an ABox and its TBox individual instance p IN C abor IN individual name C concept term abor ABox object Returns t if IN is an instance of C in abox and nil otherwise individuals related macro Description Syntax Arguments Values Checks if two individuals are directl
10. all transitive roles describe tbox describe concept describe role ABox Retrieval individual direct ty most specific instan individual types instantiators concept instances retrieve concept ins individual fillers retrieve individual retrieve related ind related individuals retrieve individual retrieve direct pred loop over aboxes all aboxes all individuals all concept assertio all role assertions all role assertions all concept assertio all role assertions describe abox describe individual Se Mie eue ds ge de ob Soa ee wok Se laure Ja fa Na a amp DOS eine e is nn biators A enpi gea e aA A Ege Mead LANGES 4 44 a gt e A A a Je fillers nsa sus we Lie as Heu apa sil ad TVLAUALS 2 iia mt bei e as filled roles viaria koht asjus as as COSSOLS is Der kaasi oh a dt Te a SE ere et co ve ns for individual for individual in domain for individual in range DNS ys ia o wa 18 be fon tes ogres ook te he eR es WS Se ssc Ob Ro da ds A d 50 50 51 51 51 52 52 52 52 53 53 53 53 54 54 54 54 59 59 59 59 56 56 56 57 57 58 58 58 59 59 59 59 60 60 60 61 61 A KRSS Sample Knowledge Base A 1 KRSS Sample TBox A 2 KRSS Sample ABox B Integrated Sample Knowledge Base vi 1 Introduction The RACER system is a knowled
11. retrieve direct predecessors 56 retrieve individual filled roles 56 retrieve individual fillers 54 retrieve related individuals 55 role hierarchy 9 role ancestors 48 role children 49 role descendants 47 role inverse 38 role offspring 48 role p 35 role parents 49 role subsumes p 35 role subsumes 34 role 35 save abox 18 save tbox 14 signature 6 signature 13 state 29 subrole 23 25 superrole 23 25 symmetric p 36 symmetric 37 taxonomy 44 tbox 19 tbox classified p 39 tbox classified 39 tbox coherent p 39 tbox coherent 39 tbox name 15 top 19 transitive role 9 23 transitive p 35 transitive 36 unique name assumption 10 value restriction 7 68
12. Domain and range restrictions expressed via GCIs define primitive role RN and RN RN2 can be approximated in RACER by define primitive role RN parents RN RN2 RACER offers the declaration of domain and range restrictions for roles These restric tions for primitive roles can be either expressed with GCIs see the examples in Figure 7 cf Buchheit et al 93 or declared via the keywords domain and range e g see the description of define primitive role in Section 5 3 page 25 3 4 Concrete Domains Racer supports reasoning over the integers and over the reals Names for values from these concrete domains are called objects Individuals can be associated with objects via so called attributes names or attributes for short Note that the set of attributes must be disjoint to the set of roles and the set of features Attributes can be declared in the signature of a TBox see below The following example is an extension of the family TBox introduced above signature atomic concepts teenager roles attributes integer age equivalent teenager and human min age 16 equivalent old teenager and human min age 18 Asking for the children of teenager reveals that old teenager is a teenager A further extensions demonstrates the usage of the real concrete domain signature atomic concepts teenager roles attributes integer age real temperature celsius real temperature fahr
13. Starting from the set C complex concept terms can be build using several operators An overview over all concept and role building operators is given in Figure 4 Boolean terms build concepts by using the boolean operators DL notation RACER syntax Negation C not C Conjunction CM MC and Ci Cp Disjunction CiU UC or Cy Cn Qualified restrictions state that role fillers have to be of a certain concept Value restric tions assure that the type of all role fillers is of the specified concept while exist restrictions require that there be a filler of that role which is an instance of the specified concept DL notation RACER syntax J3 R C some R C Y R C all R C Exists restriction Value restriction Number restrictions can specify a lower bound an upper bound or an exact number for the amount of role fillers each instance of this concept has for a certain role Only roles that are not transitive and do not have any transitive subroles are allowed in number restrictions see also the comments in Horrocks et al 99a Horrocks et al 99b The signature does not have to be specified explicitly in RACER knowledge bases the system can compute it from the all the used names in the knowledge base but specifying a signature may help avoiding errors caused by typos C CN top bottom not C and Cy Cy or Ch Ch some R C a11 R C at least n R
14. Syntax concept instances C amp optional ABN abox name current abox Arguments C concept term ABN ABox name Values List of individual names 59 retrieve concept instances function Description Gets all individuals from an ABox that are instances of the specified concept Syntax retrieve concept instances C abos Arguments C concept term abox ABox object Values List of individual names individual fillers KRSS macro Description Gets all individuals that are fillers of a role for a specified individual Syntax individual fillers IN R optional ABN abox name current abox Arguments IN individual name of the predecessor R role term ABN ABox name Values List of individual names Examples individual fillers Charlie Brown has pet individual fillers Snoopy inv has pet retrieve individual fillers function Description Gets all individuals that are fillers of a role for a specified individual Syntax retrieve individual fillers IN R abox Arguments IN individual name of the predecessor R role term abox ABox object Values List of individual names Examples retrieve individual fillers Charlie Brown has pet find abox peanuts characters P 56 retrieve related individuals function Description Syntax Arguments Values Examples See also Gets all pairs of individuals that are related via the specified relation retrieve related
15. abox consistent p 40 abox consistent 41 abox name 19 abox realized p 40 abox realized 40 add concept assertion 27 add concept axiom 23 add disjointness axiom 23 add role assertion 28 add role axioms 26 alc concept coherent 34 all aboxes 57 all atomic concepts 50 all concept assertions 58 all concept assertions for individual 57 all features 51 all individuals 57 all role assertions 58 all role assertions for individual in domain 57 all role assertions for individual in range 58 all roles 51 all tboxes 50 all transitive roles 51 assertion 9 atomic concept ancestors 46 atomic concept children 47 atomic concept descendants 45 atomic concept parents 47 atomic concept synonyms 45 atomic role ancestors 48 atomic role children 49 atomic role descendants 48 atomic role inverse 37 atomic role parents 50 attribute 8 23 66 bottom 20 check abox coherence 41 check tbox coherence 38 classify tbox 38 concept axioms 7 concept definition 8 concept eguation 8 concept term 6 concept ancestors 46 concept children 46 concept descendants 45 concept disjoint p 33 concept disjoint 32 concept eguivalent p 32 concept eguivalent 32 concept instances 53 concept is primitive p 33 concept is primitive 34 concept offspring 46 concept p 33 concept parents 47 concept satisfiable p 31 concept satisfiable 30 concept subsumes p 31 concept subsumes 31 concept synonyms
16. individual in domain IN amp optional abor current abox Arguments IN individual name abor ABox object Values List of role assertions Remarks Returns only the role assertions explicitly mentioned in the ABox not the inferred ones See also Function all role assertions on page 60 59 all role assertions for individual in range function Description Syntax Arguments Values See also Returns all role assertions for an individual from the specified ABox in which the individual is a role successor all role assertions for individual in range IN amp optional abor current abox IN individual name abor ABox object List of assertions Function all role assertions on page 60 all concept assertions function Description Syntax Arguments Values Returns all concept assertions from the specified ABox all concept assertions amp optional abor current abox abor ABox object List of assertions all role assertions function Description Syntax Arguments Values See also Returns all role assertions from the specified ABox all role assertions optional abor current abox IN individual name abor ABox object List of assertions Function all concept assertions for individual on page 59 60 describe abox function Description Syntax Arguments Values Generates a description for the specified A Box
17. individuals abox R abox role term ABox object List of pairs of individual names retrieve related individuals has pet find abox peanuts characters may yield Charlie Brown Snoopy John Arbuckle Garfield Function individuals related p on page 44 related individuals macro Description Syntax Arguments Values Examples See also Gets all pairs of individuals that are related via the specified relation related individuals R optional ABN abox name current abox R role term ABN ABox name List of pairs of individual names retrieve related individuals has pet find abox peanuts characters may yield Charlie Brown Snoopy John Arbuckle Garfield Function individuals related p on page 44 57 retrieve individual filled roles function Description This function gets all roles that hold between the specified pair of individu als Syntax retrieve individual filled roles IN IN2 abox Arguments JN individual name of the predecessor IN individual name of the role filler abor ABox object Values List of role terms Examples retrieve individual filled roles Charlie Brown Snoopy find abox peanuts characters See also Function individuals related p on page 44 retrieve direct predecessors function Description Gets all individuals that are predecessors of a role for a specified individual Sy
18. setting the value of the variables auto classify and auto realize for TBox and ABox inference respectively The lazy inference mode is activated by setting the variables to the keyword lazy Eager inference behavior can be enforced by setting the variables to eager The default value for each variable is lazy verbose which means that RACER prints a progress bar in order to indicate the state of the current inference activity if it might take some time If you want These roles are treated as roles that are neither a feature nor transitive and do not have any superroles New items are added to the TBox Note that this might lead to surprising query results e g the set of subconcepts for T contains concepts not mentioned in the TBox in any concept axiom Therefore we recommend to use a signature declaration see below These concepts are assumed to be atomic concepts 12 this for eager inferences use the value eager verbose If other values are encountered the user is responsible for calling necessary setup functions not recommended We recommend that TBoxes and ABoxes should be kept in separate files If an ABox is revised by reloading or reevaluating a file there is no need to recompute anything for the TBox However if the TBox is placed in the same file reevaluating a file presumably causes the TBox to be reinitialized and the axioms to be declared again Thus in order to answer an ABox query recomputations concern
19. state KRSS macro Description Syntax Arguments Remarks This macro asserts a set of ABox statements state amp body forms forms is a sequence of instance or related assertions This macro is supplied to be compatible with the KRSS specification It realizes an implicit progn for assertions 31 forget macro Description This macro retracts a set of ABox statements Syntax forget amp body forms Arguments forms is a sequence of instance or related assertions Remarks For answering subsequent queries the index structures for the ABox will be recomputed i e some queries might take some time e g those queries that require the realization of the ABox 6 Reasoning Modes auto classify special variable Description Possible values are lazy eager lazy verbose eager verbose nil See also Section 3 6 on page 12 auto realize special variable Description Possible values are lazy eager lazy verbose eager verbose nil See also Section 3 6 on page 12 7 Evaluation Functions and Queries 7 1 Queries for Concept Terms concept satisfiable macro Description Checks if a concept term is satisfiable Syntax concept satisfiable C optional thor current tbox Arguments C concept term tbox TBox object Values Returns t if C is satisfiable and nil otherwise Remarks For testing whether a concept term is satisfiable with respect to a TBox tbo
20. Box may use new names for roles or concepts which are not mentioned in the TBox 3 6 Inference Modes After the declaration of a TBox or an ABox RACER can be instructed to answer queries Processing the knowledge base in order to answer a query may take some time The standard inference mode of RACER ensures the following behavior Depending on the kind of query RACER tries to be as smart as possible to locally minimize computation time lazy inference mode For instance in order to answer a subsumption query w r t a TBox it is not necessary to classify the TBox However once a TBox is classified answering subsumption queries for atomic concepts is just a lookup Furthermore asking whether there exists an atomic concept in a TBox that is inconsistent tbox coherent p does not require the TBox to be classified either In the lazy mode of inference the default RACER avoids computations that are not required concerning the current query In some situations however in order to globally minimize processing time it might be better to just classify a TBox before answering a query eager inference mode A similar strategy is applied if the computation of the direct types of individuals is requested RACER requires as precondition that the corresponding TBox has to be classified If the lazy inference mode is enabled only the individuals involved in a direct types query are realized The inference behavior of RACER can be controlled by
21. Consistent pi 4 en a klint SP ee dare a abox consistent check abox coherence individual instance individual instance p individuals related individuals related p individual equal individual not equal individual p insite ek kos m seente kus ml Ora individual ir seatud tele de 8 Retrieval 8 1 TBox Retrieval TAXONOMY oh ce gas tence Dott awe An ee ote ts cOncept SyMONyMsS Hu we me den ee a vu atomic concept synonyms concept descendants atomic concept descendants concept ancestors atomic concept ancestors concept children 22 ds ab die au as go oe ue atomic concept children CONCEpPt parenes iii te RAR LEP MER A ee atomic concept parents role descendants ia oii srs we Ee ee e a atomic role descendants iv 40 40 41 41 41 41 41 42 42 42 42 42 43 43 43 44 44 44 45 45 45 45 46 46 46 46 47 47 47 48 48 48 49 49 49 49 50 8 2 role ancestors atomic role ancestor role children atomic role children role parents atomic role parents loop over tboxes all tboxes all atomic concepts all roles all features
22. R Arguments abor ABox object IN individual name of the predecessor IN3 individual name of the filler R role term Values abox Examples add role assertion find abox peanuts characters Charlie Brown Snoopy has pet add role assertion find abox peanuts characters Linus Lucy inv has brother 30 forget role assertion function Description Syntax Arguments Values Remarks Examples Retracts a role assertion from an ABox forget role assertion abox IN IN R abor ABox object IN individual name of the predecessor IN individual name of the filler R role term abox For answering subseguent gueries the index structures for the ABox will be recomputed i e some queries might take some time e g those queries that require the realization of the ABox forget role assertion find abox peanuts characters Charlie Brown Snoopy has pet forget role assertion find abox peanuts characters Linus Lucy inv has brother define distinct individual KRSS macro Description Syntax Arguments Values Remarks This statement asserts that an individual is distinct to all other individuals in the ABox define distinct individual IN IN name of the individual IN Because the unigue name assumption holds in RACER all individuals are distinct This function is supplied to be compatible with the KRSS specifi cation
23. RACER User s Guide and Reference Manual Version 1 6 Volker Haarslev Ralf Moller haarslev moeller informatik uni hamburg de University of Hamburg Computer Science Department Vogt Kolln Str 30 22527 Hamburg Germany July 26 2001 Contents 1 Introduction 2 Obtaining and Running RACER 2 1 System Installation ee ee i Ma OE AG Pee 2 2 Sample Session 54 040205 le aa a eee 2 3 Naming Conventions le pris ze mm Me PAS AE tan ie de Re re OR Be a 3 RACER Knowledge Bases 3 1 Concept Language gt is eee Seok ae Re ehe Boe eee ke Oe Be da 3 2 Concept Axioms and Terminology 3 3 Role Declarations 3 4 Conerete Domains oota 54 225522 SRD ds de GR a nu 3 0 GABox Assertions 4311 A Mobla A bate IE 25 ot Set a ge 3 6 Inference Modes 3 7 Retraction and Incremental Additions 4 Knowledge Base Management Functions 4 1 TBox Management roto ia be a AAA ee ce aus NST DOR ets and Be A es as YS ne ea Pe ee at ee t oe naa PCAC DORs a Bet Peseta as By ith ee be ie oS Be ere ey Ei be Bo signature oe coem popne y RR a ee AE oe ce ensure tbox signature CUTTONC EDOX on o Gao se Wake a oS ee eae ek Da SAVES DOK on to ae Yee te ten dot ee Mod Be Ae Ee le ke oF a E 4 2 ABox Management in ab A 5 5 moss a ANUP ADO Ke ee ee Le sir ensure abox signature i
24. TBN TBox name Returns t if there is an inconsistent atomic concept otherwise it returns nil This macro uses tbox coherent p 7 4 ABox Evaluation Functions Al realize abox function Description This function checks the consistency of the ABox and computes the most specific concepts for each individual in the ABox Syntax realize abox amp optional abor current abox Arguments abor ABox object Values abox Remarks This Function needs to be executed before queries can be posed If the TBox has changed and is classified again the ABox has to be realized too abox realized p function Description Returns t if the specified ABox object has been realized Syntax abox realized p optional abor current abox Arguments abor ABox object Values Returns t if abox has been realized and nil otherwise abox realized macro Description Returns t if the specified ABox object has been realized Syntax abox realized optional ABN abox name current abox Arguments ABN ABox name Values Returns t if ABN has been realized and nil otherwise 7 5 ABox Queries abox consistent p function Description Checks if the ABox is consistent e g it does not contain a contradiction Syntax abox consistent p amp optional abor current abox Arguments abor ABox object Values Returns t if abox is consistent and nil otherwise 42 abox consistent macro
25. alues Gets the roles from the TBox that directly subsume the given role in the role hierarchy role parents amp optional TBN tbox name current tbox R role term TBN TBox name List of role terms 51 atomic role parents function Description Gets the roles from the TBox that directly subsume the given role in the role hierarchy Syntax atomic role parents tbox Arguments R role term tbox TBox object Values List of role terms loop over tboxes function Description Iterator function for all TBoxes Syntax loop over tboxes tbhox variable loop clause Arguments tboz variable variable for a TBox object loop clause loop clause all tboxes function Description Returns the names of all known TBoxes Syntax all tboxes Values List of TBox names all atomic concepts function Description Returns all atomic concepts from the specified TBox Syntax all atomic concepts amp optional tbox current tbox Arguments thor TBox object Values List of concept names Remarks all atomic concepts find tbox my tbox 52 all roles function Description Returns all roles and features from the specified TBox Syntax all roles optional tbox current tbox Arguments thor TBox object Values List of role terms Examples all roles find tbox my tbox all features function Description Returns all fea
26. am object tbox or abox The description is written to stream 8 2 ABox Retrieval individual direct types KRSS macro Description Syntax Arguments Values Gets the most specific atomic concepts of which an individual is an instance individual direct types IN optional ABN abox name current abox IN individual name ABN ABox name List of name sets 54 most specific instantiators function Description Gets the most specific atomic concepts of which an individual is an instance Syntax most specific instantiators IN abor Arguments IN individual name abor ABox object Values List of name sets individual types KRSS macro Description Gets all atomic concepts of which the individual is an instance Syntax individual types IN amp optional ABN abox name current abox Arguments IN individual name ABN ABox name Values List of name sets Remarks This is the transitive closure of the KRSS macro individual direct types instantiators function Description Gets all atomic concepts of which the individual is an instance Syntax instantiators IN abox Arguments IN individual name abor ABox object Values List of name sets Remarks This is the transitive closure of the function most specific instantiators concept instances KRSS macro Description Gets all individuals from an ABox that are instances of the specified concept
27. bution Then follow the instructions in the file readme txt found in the directory lt filename gt It is important that you load the file load racer lisp from the Lisp Listener Do not evaluate or compile this file This file declares logical pathnames which are used in the example TBoxes 2 2 Sample Session All the files used in this example are in the directory racer examples The queries are in the file family gueries lisp 333 the following forms are assumed to be contained in a 333 file racer examples family tbox lisp 333 initialize the TBox family in tbox family IRACER stands for Reasoner for ABoxes and Concept Expressions Renamed 333 supply the signature for this TBox signature atomic concepts person human female male woman man parent mother father grandmother aunt uncle sister brother roles has child parent has descendant has descendant transitive t has sibling has sister parent has sibling has brother parent has sibling has gender feature t 335 domain range restrictions for roles implies top all has child person implies some has child top parent implies some has sibling top or sister brother implies top all has sibling or sister brother implies top all has sister some has gender female implies top all has brother some has gender male 333 the concepts implies person and human some has gender or female male di
28. cter Baseball Player roles has pet has dog parents has pet domain human range dog has coach feature t Signature for an ABox signature individuals Charlie Brown Snoopy Signature for a TBox and an ABox signature atomic concepts Character Baseball Player roles has pet has dog parents has pet domain human range dog has coach feature t individuals Charlie Brown Snoopy See also Section Sample Session on page 2 and page 3 For role definitions see define primitive role on page 25 ensure tbox signature function Description Defines the signature for a TBox and initializes the TBox Syntax ensure tbox signature thor amp key atomic concepts nil roles nil Arguments thor is a TBox name or a TBox object atomic concepts is a list of all the concept names specifying C roles is a list of all role declarations thereby also specifying R 15 current tbox special variable Description The variable current tbox refers to the current TBox object It is set by the function init tbox or by the macro in tbox save tbox function Description Syntax Arguments Values Remarks Examples If a pathname is specified a TBox is saved to a file In case a stream is specified the TBox is written to the stream the stream must already be open and the keywords if exists and if does not exist are ignored save tbox pathname or strea
29. current tbox C concept term TBN TBox name List of name sets Is the equivalent macro for the KRSS macro concept offspring which is also supplied in RACER 48 atomic concept children function Description Gets the direct subsumees of the specified concept in the TBox Syntax atomic concept children C tbox Arguments C concept term tbox TBox object Values List of name sets concept parents KRSS macro Description Gets the direct subsumers of the specified concept in the TBox Syntax concept parents C optional TBN tbox name current tbox Arguments C concept term TBN TBox name Values List of name sets atomic concept parents function Description Gets the direct subsumers of the specified concept in the TBox Syntax atomic concept parents C thor Arguments C concept term tbox TBox object Values List of name sets role descendants KRSS macro Description Gets all roles from the TBox that the given role subsumes Syntax role descendants R koptional TBN tbox name current tbox Arguments R role term TBN TBox name Values List of role terms Remarks This macro is the transitive closure of the macro role children 49 atomic role descendants function Description Syntax Arguments Values Remarks Gets all roles from the TBox that the given role subsumes atomic role descendants R tbox R role te
30. describe abox amp optional abox current abox stream standard output abor ABox object stream open stream object abox The description is written to stream describe individual function Description Syntax Arguments Values Generates a description for the individual from the specified ABox describe individual IN amp optional abox current abox stream standard output IN individual name abor ABox object stream open stream object IN The description is written to stream 61 A KRSS Sample Knowledge Base The following knowledge base is specified in KRSS syntax It is a version of the knowledge base used in the Sample Session on page 1 A 1 KRSS Sample TBox 333 the following forms are assumed to be contained in a 333 file racer examples family tbox krss lisp 333 initialize the TBox family in tbox family init t 33 the roles define primitive role has child parents has descendant define primitive role has descendant transitive t define primitive role has sibling define primitive role has sister parents has sibling define primitive role has brother parents has sibling define primitive attribute has gender 335 domain range restrictions for roles implies top all has child person implies some has child top parent implies some has sibling top or sister brother implies top all has sibling or sister brother implie
31. eclares that the new role is a symmetric This is equivalent to declaring that the new role s inverse is the role itself reflexive if bound to t declares that the new role is reflexive currently only supported for ALCH If feature is bound to t the value of reflexive is ignored inverse provides a name for the inverse role of RN This is equivalent to inv RN The inverse role of RN has no user defined name if inverse is bound to nil domain provides a concept term defining the domain of role RN This is equivalent to adding the axiom implies at least 1 RN C if domain is bound to the concept term C No domain is declared if domain is bound to nil range provides a concept term defining the range of role RN This is equivalent to adding the axiom implies top all RN D if range is bound to the concept term D No range is declared if range is bound to nil parents provides a list of superroles for the new role The role RN has no superroles if parents is bound to nil If only a single superrole is specified the keyword parent may alternatively be used see the examples This function combines several KRSS functions for defining properties of a role For example the conjunction of roles can be expressed as shown in the first example below A role that is declared to be a feature cannot be transitive A role with a feature as a parent has to be a feature itself A role with transitive subroles may not be used in
32. enheit 10 equivalent teenager and human min age 16 equivalent old teenager and human min age 18 equivalent human with feaver and human gt temperature celsius 38 5 equivalent seriously ill human and human gt temperature celsius 42 0 Obviously Racer determines that the concept seriously ill human is subsumed by human with feaver For the reals Racer supports linear equations and inequations Thus we could add the following statement to the knowledge base in order to make sure the relations between the two attributes temperature fahrenheit and temperature celsius is properly represented implies top temperature fahrenheit 1 8 temperature celsius 32 If a concept seriously ill human 1 is defined as equivalent seriously ill human 1 and human gt temperature fahrenheit 107 6 Racer recognizes the subsumption relationship with human with feaver and the synonym relationship with seriously ill human In an ABox it is possible to set up constraints between individuals constrained eve temp eve temperature fahrenheit constrained doris temp doris temperature celsius constraints temp eve 102 56 temp doris 39 5 Now asking for the direct types of eve and doris reveals that both individuals are instances of human with feaver In the following Abox there is an inconsistency constrained eve temp eve temperature fahrenheit constrained doris temp doris temperature celsi
33. erroles for the new role The role AN has no superroles if parents is bound to nil If only a single superrole is specified the keyword parent may alternatively be used see examples This macro is supplied to be compatible with the KRSS specification It is re dundant since the macro define primitive role can be used with feature t This function combines several KRSS functions for defining properties of an attribute An attribute cannot be transitive A role with a feature as a parent has to be a feature itself define primitive attribute has mother domain child range mother parents has parents define primitive attribute has best friend inverse best friend of parent has friends Macro signature on page 14 Section 3 3 and Figure 7 on page 10 for domain and range restrictions 27 add role axioms function Description Adds a role to a TBox Syntax add role axioms thor RN amp key transitive nil feature nil symmetric nil reflexive nil inverse nil domain nil range nil parents nil Arguments thor TBox object to which the role is added RN role name transitive if bound to t declares that the role is transitive feature if bound to t declares that the new role is a feature if feature is bound to t symmetric if bound to t declares that the new role is a symmetric This is equivalent to declaring that the new role s inverse is the role itself reflexive if bound to t dec
34. ffered by RACER macro interfaces and function interfaces are provided For macro forms the TBox or ABox arguments are optional If no TBox or ABox is specified the current tbox or current abox is taken respectively However for the functional counterpart of a macro the TBox or ABox argument is not optional For functions which do not have macro coun terparts the TBox or ABox argument may or may not be optional Furthermore if an argument tbox or abox is specified in this documentation a name a symbol can be used as well 3 RACER Knowledge Bases In description logic systems a knowledge base is consisting of a TBox and an ABox The conceptual knowledge is represented in the TBox and the knowledge about the instances of a domain is represented in the ABox For more information about the description logic SHZQ supported by RACER see Horrocks et al 2000 Note that RACER assumes the unique name assumption for ABox individuals see also Haarslev and M ller 2000 where the logic supported by RACER s precursor RACE is described The unique name assumption does not hold for the description logic SHTQ as introduced in Horrocks et al 2000 3 1 Concept Language The content of RACER TBoxes includes the conceptual modeling of concepts and roles as well The modelling is based on the signature which consists of two disjoint sets the set of concept names C also called the atomic concepts and the set R containing the role names
35. ge representation system that implements a highly opti mized tableaux calculus for a very expressive description logic It offers reasoning services for multiple TBoxes and for multiple ABoxes as well The system implements the descrip tion logic ALCOHI p also known as SHTQ see Horrocks et al 2000 This is the basic logic ALC augmented with qualifying number restrictions role hierarchies inverse roles and transitive roles RACER supports the specification of general terminological axioms A TBox may contain general concept inclusions GCIs which state the subsumption relation between two con cept terms Multiple definitions or even cyclic definitions of concepts can be handled by RACER RACER supports most of the functions specified in the Knowledge Representation System Specification KRSS for details see Patel Schneider and Swartout 93 RACER is implemented in ANSI Common Lisp and has been developed at the University of Hamburg 2 Obtaining and Running RACER The RACER system can be obtained from the following web site http kogs www informatik uni hamburg de race 2 1 System Installation For the Macintosh execute the self extracting archive lt filename gt sea For UNIX and Windows systems decompress the archive file after downloading For UNIX use the command gzip dc lt filename gt tar gz tar xf Under Windows unzip the file lt filename gt zip This creates the files and directories of the distri
36. individual name abor abox object Remarks Because the unique name assumption holds in RACER this macro always returns t for individuals with different names This macro is just supplied to be compatible with the KRSS individual p function Description Checks if IN is a name of an individual mentioned in an ABox abox Syntax individual p IN amp optional abox current abox Arguments IN individual name abor ABox object Values Returns t if IN is a name of an individual and nil otherwise individual macro Description Checks if IN is a name of an individual mentioned in an ABox ABN Syntax individual IN amp optional ABN abox name current abox Arguments IN individual name ABN ABox name Values Returns t if JN is a name of an individual and nil otherwise 45 8 Retrieval If the retrieval refers to concept names RACER always returns a set of names for each concept name A so called name set contains all synonyms of an atomic concept in the TBox 8 1 TBox Retrieval taxonomy function Description Returns the whole taxonomy for the specified TBox Syntax taxonomy amp optional thor current tbox Arguments thor TBox object Values A list of triples each of it consisting of a name set the atomic concept CN and its synonyms list of concept parents name sets each entry being a list of a concept parent of CN and its synonyms list of concept children name se
37. ing the TBox might be necessary So if different ABoxes are to be tested they should probably be located separately from the associated TBoxes in order to save processing time During the development phase of a TBox it might be advantageous to call inference services directly For instance during the development phase of a TBox it might be useful to check which atomic concepts in the TBox are inconsistent by calling check tbox coherence This service is usually much faster than calling classify tbox However if an application prob lem can be solved for example by checking whether a certian ABox is consistent or not see the function abox consistent p it is not necessary to call either check tbox coherence or classify tbox For all queries RACER ensures that the knowledge bases are in the ap propriate states This behavior usually guarantees minimum runtimes for answering queries 3 7 Retraction and Incremental Additions RACER offers constructs for retracting ABox assertions see forget forget concept assertion and forget role assertion If a query has been an swered and some assertions are retracted then RACER might be forced to realize the ABox again i e after retractions some queries might take some time to answer RACER also supports incremental additions to ABoxes i e assertions can be added even after queries have been answered However the internal data structures used for anwering queries are recomputed from scratch This
38. isfiable during the development phase of a TBox There is no need to call the function check tbox coherence if for instance a certain ABox is to be checked for consistency with abox consistent p 40 tbox classified p function Description Syntax Arguments Values It is checked if the specified TBox has already been classified tbox classified p optional tbor current tbox tbox TBox object Returns t if the specified TBox has been classified otherwise it returns nil tbox classified macro Description Syntax Arguments Values It is checked if the specified TBox has already been classified tbox classified optional TBN tbox name current tbox TBN TBox name Returns t if the specified TBox has been classified otherwise it returns nil tbox coherent p function Description Syntax Arguments Values Remarks This function checks if there are any unsatisfiable atomic concepts in the given TBox tbox coherent p amp optional thor current tbox tbox TBox object Returns nil if there is an inconsistent atomic concept otherwise it returns t This function calls check tbox coherence if necessary tbox coherent macro Description Syntax Arguments Values Remarks Checks if there are any unsatisfiable atomic concepts in the current or spec ified TBox tbox coherent amp optional TBN tbox name current tbox
39. lares that the new role is reflexive currently only supported for ALCH If feature is bound to t the value of reflexive is ignored inverse provides a name for the inverse role of RN is equivalent to inv RN The inverse role of RN has no user defined name if inverse is bound to nil domain provides a concept term defining the domain of role RN equivalent to adding the axiom implies at least 1 RN C if domain is bound to the concept term C No domain is declared if domain is bound to nil range provides a concept term defining the range of role RN equivalent to adding the axiom implies top all RN D if range is bound to the concept term D No range is declared if range is bound to nil parents providing a single role or a list of superroles for the new role The role RN has no superroles if parents is bound to nil Values tbox Remarks For each role RN there may be only one call to add role axioms per TBox See also Section 3 3 and Figure 7 on page 10 for domain and range restrictions 5 4 Assertions 28 instance KRSS macro Description Syntax Arguments Examples Builds a concept assertion asserts that an individual is an instance of a concept instance IN C IN G individual name concept term instance Lucy Person instance Snoopy and Dog Cartoon Character add concept assertion Junction Description Builds an assertion and adds it to an ABox S
40. m amp optional thor current tbox amp key syntax krss transformed nil if exists supersede if does not exist create pathname or stream is the pathname of a file or an output stream tbox TBox object syntax indicates the syntax of the TBox only krss is currently imple mented transformed if bound to t the TBox is saved in the format after preprocess ing by RACER if exists specifies the action taken if a file with the specified name already exists All keywords for the Lisp function with open file are sup ported The default is supersede if does not exist specifies the action taken if a file with the specified name does not yet exist All keywords for the Lisp function with open file are supported The default is create TBox object A file may contain several TBoxes The usual way to load a TBox file is to use the Lisp function load save tbox project TBoxes tbox one lisp save tbox project TBoxes final tbox lisp find tbox tbox one if exists error 16 find tbox function Description Returns a TBox object with the given name among all TBoxes Syntax find tbox TBN optional errorp t Arguments TBN is the name of the TBox to be found errorp if bound to t an error is signaled if the TBox is not found Values TBox object Remarks This function can also be used to get rid of TBoxes or rename TBoxes as shown in the examples Examples find tbox m
41. male equivalent parent and person some has child person equivalent mother and woman parent equivalent father and man parent equivalent grandmother and mother some has child some has child person equivalent aunt and woman some has sibling parent equivalent uncle and man some has sibling parent equivalent brother and man some has sibling person equivalent sister and woman some has sibling person 335 Alice is the mother of Betty and Charles instance alice mother related alice betty has child related alice charles has child 335 Betty is mother of Doris and Eve instance betty mother related betty doris has child related betty eve has child 64 333 Charles is the brother of Betty and only Betty instance charles brother related charles betty has sibling 335 Closing the role has sibling for charles instance charles at most 1 has sibling 355 Doris has the sister Eve related doris eve has sister 333 Eve has the sister Doris related eve doris has sister References Buchheit et al 93 M Buchheit F M Donini amp A Schaerf Decidable Reasoning in Ter minological Knowledge Representation Systems in Journal of Artificial Intelligence Research 1 pp 109 138 1993 Haarslev and M ller 2000 Haarslev V and M ller R 2000 Expressive ABox reasoning with number restrictions role hierarchies and transitively closed roles i
42. might take some time If an ABox is used for hypothesis generation e g for testing whether the assertion C can be added without causing an inconsistency we recommend using the instance checking inference service If individual instance i not C returns t i C cannot be added to the ABox Now let us assume we can add i C and afterwards want to test whether i D can be added without causing an inconsistency In this case it might be faster not to add i C directly but to check whether individual instance i and C not D returns t The reason is that in this case the index structures for the ABox are not recomputed 13 4 Knowledge Base Management Functions This section documents the functions for managing TBoxes and ABoxes and for specifying queries 4 1 TBox Management in tbox macro Description The TBox with the specified name is taken or a new TBox with that name is generated and bound to the variable current tbox Syntax in tbox TBN amp key init t Arguments TBN is the name of the TBox init boolean indicating if the TBox should be initialized Remarks Usually this macro is used at top of a file containing a TBox This macro can also be used to create new TBoxes The specified TBox is the current tbox until in tbox is called again or the variable current tbox is manipulated directly Examples in tbox peanuts implies Piano Player Character See also Macro signature on page 14 init tbox
43. n Proceedings of Seventh International Conference on Principles of Knowledge Representation and Reasoning KR 2000 Cohn A Giunchiglia F and Selman B editors Brecken ridge Colorado USA April 11 15 2000 pages 273 284 Horrocks et al 99a I Horrocks U Sattler S Tobies Practical Reasoning for Descrip tion Logics with Functional Restrictions Inverse and Transitive Roles and Role Hier archies Proceedings of the 1999 Workshop Methods for Modalities M4M 1 Ams terdam 1999 Horrocks et al 99b I Horrocks U Sattler S Tobies A Description Logic with Transitive and Converse Roles Role Hierarchies and Qualifying Number Restrictions Technical Report LTCS 99 08 RWTH Aachen 1999 Horrocks et al 2000 Horrocks I Sattler U and Tobies S 2000 Reasoning with indi viduals for the description logic SHZQ In MacAllester D editor Proceedings of the 17th International Conference on Automated Deduction CADE 17 Lecture Notes in Computer Science Germany Springer Verlag Patel Schneider and Swartout 93 P F Patel Schneider B Swartout Description Logic Knowledge Representation System Specification from the KRSS Group of the ARPA Knowledge Sharing Effort November 1993 The paper is available as http www db research bell labs com user pfps papers krss spec ps 65 Index auto classify 30 auto realizex 30 bottom 20 current abox 17 current tbox 14 top 19
44. n knowledge base current abox save abox find abox abox name 5 Knowledge Base Declarations 5 1 Built in Concepts top top bottom bottom 5 2 Concept Axioms IMPliES o e ses Mot equivalent ATSJOINE gg re ge Se ir sat define primitive concept define concept define disjoint primitive concept add concept axiom add disjointness axiom 5 3 Role Declarations define primitive role define primitive attribute add role axioms 5 4 Assertions instance add concept assertion forget concept assertion related oroni 55965 an 8 18 1 sn add role assertion forget role assertion define distinct individual 17 17 17 17 18 18 19 19 20 20 21 21 21 21 21 22 22 22 23 23 23 24 24 25 25 25 26 27 28 28 29 29 29 30 30 31 31 6 Reasoning Modes KAUTO CLASSITY as LU Soe a Be after a auto realize se 4 Sa we Re Oe ee 7 Evaluation Functions and Queries 7 1 7 2 7 3 Queries for Concept Terms concept satisfiable concept satisfiable p concept subsumes concept subsumes p concept equivalent concept equivalent p CONCEPESATE JOER eec ue are he
45. ncept equivalent macro Description Checks if the two concepts are equivalent in the given TBox Syntax concept equivalent C C2 optional tbox current tbox Arguments C1 C2 concept term tbox TBox object Values Returns t if C and C2 are equivalent concepts in tbox and nil otherwise Remarks For testing whether two concept terms are equivalent with respect to a TBox tboz See also Function atomic concept synonyms on page 47 and function concept subsumes p on page 33 concept equivalent p function Description Checks if the two concepts are equivalent in the given T Box Syntax concept equivalent p C1 C2 tbox Arguments C1 C2 concept terms tbox TBox object Values Returns t if C1 and C2 are equivalent concepts in tbox and nil otherwise Remarks For testing whether two concept terms are equivalent with respect to a TBox tbox If the equality is to be tested without reference to a TBox nil can be used See also Function atomic concept synonyms on page 47 and function concept subsumes p on page 33 macro concept disjoint Description Syntax Arguments Values Remarks Checks if the two concepts are disjoint e g no individual can be an instance of both concepts concept disjoint C1 C2 amp optional thor current tbox Ci C2 concept term tbox TBox object Returns t if C1 and C2 are disjoint with respect to tbox and nil otherwise For testing whether two c
46. nd only Betty instance charles brother related charles betty has sibling 335 Closing the role has sibling for charles instance charles at most 1 has sibling 355 Doris has the sister Eve related doris eve has sister 333 Eve has the sister Doris related eve doris has sister B Integrated Sample Knowledge Base This section shows an integrated version of the family knowledge base 333 the following forms are assumed to be contained in a 333 file racer examples family kb lisp in knowledge base family smith family 63 signature atomic concepts person human female male woman man parent mother father grandmother aunt uncle sister brother roles has descendant transitive t has child parent has descendant has sibling has sister parent has sibling has brother parent has sibling has gender feature t individuals alice betty charles doris eve 335 domain range restrictions for roles implies top all has child person implies some has child top parent implies some has sibling top or sister brother implies top all has sibling or sister brother implies top all has sister some has gender female implies top all has brother some has gender male 333 the concepts implies person and human some has gender or female male disjoint female male implies woman and person some has gender female implies man and person some has gender
47. not exist are ignored Syntax save abox pathname or stream amp optional abor current abox amp key syntax krss transformed nil if exists supersede if does not exist create Arguments pathname or stream is the name of the file or an output stream abor ABox object syntax indicates the syntax of the TBox only krss is currently imple mented transformed if bound to t the ABox is saved in the format it has after preprocessing by RACER if exists specifies the action taken if a file with the specified name already exists All keywords for the Lisp function with open file are sup ported The default is supersede if does not exist specifies the action taken if a file with the specified name does not yet exist All keywords for the Lisp function with open file are supported The default is create Values ABox object Remarks A file may contain several A Boxes The usual way to load an ABox file is to use the Lisp function load Examples save abox project ABoxes abox one lisp save abox project ABoxes final abox lisp find abox abox one if exists error find abox function Description Finds an ABox object with a given name among all ABoxes Syntax find abox ABN amp optional errorp t Arguments ABN is the name of the ABox to be found errorp if bound to t an error is signaled if the ABox is not found Values ABox object Remarks This function can also be u
48. nships between roles If R is a super role of Ra then for all pairs of individuals between which Ra holds R must hold too In the current implementation the specified superrole relations may not be cyclic If a role has a superrole its properties are not in every case inherited by the subrole The properties of a declared role induced by its superrole are shown in Figure 6 The table should be read as follows For example if a role RN is declared as a simple role and it has a feature RN as a superrole then RN will be a feature itself Superrole RN RIRE F Subrole RN R RIR F declared as R REIR element of F E F F Figure 6 Conflicting declared and inherited role properties The combination of a feature having a transitive superrole is not allowed and features cannot be transitive Note that transitive roles and roles with transitive subroles may not be used in number restrictions RACER does not support role terms as specified in the KRSS However a role being the conjunction of other roles can as well be expressed by using the role hierarchy cf Buchheit et al 93 The KRSS like declaration of the role KRSS DL notation define primitive role RN domain C A RN T CC define primitive role RN range D TC V RN D RACER Syntax DL notation define primitive role RN domain C A RN T CC define primitive role RN range D TC V RN D Figure 7
49. ntax retrieve direct predecessors R IN abox Arguments R role term IN individual name of the role filler abor ABox object Values List of individual names Examples retrieve direct predecessors has pet Snoopy find abox peanuts characters loop over aboxes function Description Iterator function for all ABoxes Syntax loop over aboxes abox variable loop clause Arguments aboz variable variable for a ABox object loop clause loop clause 58 all aboxes function Description Returns the names of all known ABoxes Syntax all aboxes Values List of ABox names all individuals function Description Returns all individuals from the specified ABox Syntax all individuals amp optional abor current abox Arguments abor ABox object Values List of individual names all concept assertions for individual function Description Returns all concept assertions for an individual from the specified ABox Syntax all concept assertions for individual IN amp optional abor current abox Arguments IN individual name abor ABox object Values List of concept assertions See also Function all concept assertions on page 60 all role assertions for individual in domain function Description Returns all role assertions for an individual from the specified ABox in which the individual is the role predecessor Syntax all role assertions for
50. number restrictions define primitive role conjunctive role parents R 1 R n define primitive role has descendant transitive t inverse descendant of parent has child define primitive role has children inverse has parents domain parent range children Macro signature on page 14 Section 3 3 and Figure 7 on page 10 for domain and range restrictions 26 define primitive attribute KRSS macro with changes Description Syntax Arguments Remarks Examples See also Defines an attribute define primitive attribute AN amp key symmetric nil inverse nil domain nil range nil parents nil AN attribute name symmetric if bound to t declares that the new role is a symmetric This is equivalent to declaring that the new role s inverse is the role itself inverse provides a name for the inverse role of AN This is equivalent to inv AN The inverse role of AN has no user defined name if inverse is bound to nil domain provides a concept term defining the domain of role AN This is equivalent to adding the axiom implies at least 1 AN C if domain is bound to the concept term C No domain is declared if domain is bound to nil range provides a concept term defining the range of role AN This is equivalent to adding the axiom implies top all AN D if range is bound to the concept term D No range is declared if range is bound to nil parents provides a list of sup
51. o roles are subsuming each other Syntax role subsumes p Ri R thor Arguments role term of the subsuming role Ra role term of the subsumed role tbox TBox object Values Returns t if R is a parent role of Ro role p function Description Checks if R is a role term for a role in the specified TBox Syntax role p R optional tbox current tbox Arguments R role term tbox TBox object Values Returns t if R is a known role term and nil otherwise role macro Description Checks if R is a role term for a role in the specified TBox Syntax role R optional TBN tbox name current tbox Arguments R role term TBN TBox name Values Returns t if R is a known role term and nil otherwise transitive p function Description Syntax Arguments Values Checks if R is a transitive role in the specified TBox transitive p amp optional thor current tbox R tbox role term TBox object Returns t if the role R is transitive in thor and nil otherwise 37 transitive macro Description Checks if R is a transitive role in the specified TBox Syntax transitive R amp optional TBN tbox name current tbox Arguments R role term TBN TBox name Values Returns t if the role R is transitive in TBN and nil otherwise feature p function Description Checks if R is a feature in the specified TBox Syntax feature p R amp optional thor current tbox
52. oncept L Syntax bottom Remarks The concepts bottom and bottom are synonyms These concepts are ele ments of every TBox 5 2 Concept Axioms This section documents the macros and functions for specifying concept axioms The dif ferent concept axioms were already introduced in section 3 2 Please note that the concept axioms define primitive concept define concept and define disjoint primitive concept have the semantics given in the KRSS specification only if they are the only concept axiom defining the concept CN in the terminology This is not checked by the RACER system implies macro Description Defines a GCI between Ci and C2 Syntax implies C1 C2 Arguments C1 C2 concept term Remarks C4 states necessary conditions for C2 This kind of facility is an addendum to the KRSS specification Examples implies Grandmother and Mother Female implies and some has sibling Sister some has sibling Twin exactly 1 has sibling and Twin all has sibling Twin sister 22 equivalent macro Description States the equality between two concept terms Syntax equivalent C1 C2 Arguments C1 C2 concept term Remarks This kind of concept axiom is an addendum to the KRSS specification Examples equivalent Grandmother and Mother some has child Parent equivalent and polygon exactly 4 has angle and polygon exactly 4 has edges disjoint macro Description This axiom s
53. oncept terms are disjoint with respect to a TBox tbox If the disjointness is to be tested without reference to a TBox nil can be used 34 concept disjoint p function Description Syntax Arguments Values Remarks Checks if the two concepts are disjoint e g no individual can be an instance of both concepts concept disjoint p C C2 thor C1 C2 concept term tbox TBox object Returns t if Ci and C2 are disjoint with respect to tbox and nil otherwise For testing whether two concept terms are disjoint with respect to a TBox tbox If the disjointness is to be tested without reference to a TBox nil can be used concept p function Description Checks if CN is a concept name for a concept in the specified TBox Syntax concept p CN amp optional thor current tbox Arguments CN concept name tbox TBox object Values Returns t if CN is a name of a known concept and nil otherwise concept macro Description Checks if CN is a concept name for a concept in the specified TBox Syntax concept CN amp optional TBN current tbox Arguments CN concept name TBN TBox name Values Returns t if CN is a name of a known concept and nil otherwise concept is primitive p function Description Checks if CN is a concept name of a so called primitive concept in the specified TBox Syntax concept is primitive p CN amp optional tbox current tbox Arguments CN conce
54. oncepts of the concept man CL USER 4 concept descendants man UNCLE BOTTOM BOTTOM BROTHER FATHER 333 get all transitive roles in the TBox family CL USER 5 all transitive roles HAS DESCENDANT 333 the following forms are assumed to be contained in a 333 file racer examples family abox lisp 333 initialize the ABox smith family and use the TBox family in abox smith family family 333 supply the signature for this ABox signature individuals alice betty charles doris eve 335 Alice is the mother of Betty and Charles instance alice mother related alice betty has child related alice charles has child 335 Betty is mother of Doris and Eve instance betty mother related betty doris has child related betty eve has child Charles is the brother of Betty and only Betty instance charles brother related charles betty has sibling 333 Closing the role has sibling for Charles instance charles at most 1 has sibling 355 Doris has the sister Eve related doris eve has sister 333 Eve has the sister Doris related eve doris has sister doris has child betty mother has has sister child alice mother has sibling VE charles and brother at most 1 has sibling Figure 3 Depiction of the ABox smith family with the explicitly given information being shown The RACER Session 333 now load the ABox CL USER 6 load racer examples family abox lisp
55. pt Axioms and Terminology RACER supports several kinds of concept axioms General concept inclusions GCIs state the subsumption relation between two concept terms DL notation Ci E Ca RACER syntax implies C1 C2 Concept equations state the equivalence between two concept terms DL notation Ci Ca RACER syntax equivalent C1 C2 Concept disjointness axioms state the disjointness between several concepts Disjoint concepts do not have instances in common DL notation C1 N NC L RACER syntax disjoint Ci Cy Actually a concept equation C C2 can be expressed by the two GCIs Ci E Cy and C2 E C The disjointness of the concepts Ci Cn can also be expressed by GCIs There are also separate forms for concept axioms with just concept names on their left hand sides These concept axioms implement special kinds of GCIs and concept equations But concept names are only a special kind of concept terms so these forms are just syntactic sugar They are added to the RACER system for historical reasons and for compatibility with KRSS These concept axioms are Primitive concept axioms state the subsumption relation between a concept name and a concept term DL notation CN E C RACER syntax define primitive concept CN C Concept definitions state the eguality between a concept name and a concept term DL notation CN C RACER syntax define concept CN C Concept axioms may be cyclic in RACER There ma
56. pt name tbox TBox object Values Returns t if CN is a name of a known primitive concept and nil otherwise 39 concept is primitive macro Description Syntax Arguments Values Checks if CN is a concept name of a so called primitive concept in the specified TBox concept is primitive p CN optional TBN tbox name current tbox CN concept name TBN TBox name Returns t if CN is a name of a known primitive concept and nil otherwise alc concept coherent function Description Syntax Arguments Remarks 7 2 Role Tests the satisfiability of a Ki K4 m or 54 formula encoded as an ALC concept alc concept coherent C key logic K C concept term logic specifies the logic to be used K modal Kin K4 modal K4 m all roles are transitive 54 modal S4 m all roles are transitive and reflexive If no logic is specified the logic K is chosen This function can only be used for ALC concept terms so number restrictions are not allowed Queries role subs umes KRSS macro Description Syntax Arguments Values Checks if two roles are subsuming each other role subsumes R R optional TBN tbox name current tbox Ri role term of the subsuming role Ro role term of the subsumed role TBN TBox name Returns t if R is a parent role of R 36 role subsumes p function Description Checks if tw
57. rm tbox TBox object List of role terms This function is the transitive closure of the function atomic role descendants role ancestors KRSS macro Description Syntax Arguments Values Gets all roles from the TBox that subsume the given role in the role hierar chy role ancestors R amp optional TBN tbox name current tbox R role term TBN TBox name List of role terms atomic role ancestors function Description Syntax Arguments Values Gets all roles from the TBox that subsume the given role in the role hierar chy atomic role ancestors R tbox R role term tbox TBox object List of role terms 50 role children macro Description Syntax Arguments Values Remarks Gets all roles from the TBox that are directly subsumed by the given role in the role hierarchy role children R koptional TBN tbox name current tbox R role term TBN TBox name List of role terms This is the eguivalent macro to the KRSS macro role offspring which is also supplied by the RACER system atomic role children function Description Syntax Arguments Values Gets all roles from the TBox that are directly subsumed by the given role in the role hierarchy atomic role children R thor R role term tbor TBox object List of role terms role parents KRSS macro Description Syntax Arguments V
58. s top all has sister some has gender female implies top all has brother some has gender male 333 the concepts define primitive concept person and human some has gender or female male define disjoint primitive concept female gender top define disjoint primitive concept male gender top define primitive concept woman and person some has gender female define primitive concept man and person some has gender male define concept parent and person some has child person define concept mother and woman parent define concept father and man parent define concept grandmother and mother some has child some has child person 62 define concept aunt and woman some has sibling parent define concept uncle and man some has sibling parent define concept brother and man some has sibling person define concept sister and woman some has sibling person A 2 KRSS Sample ABox 333 the following forms are assumed to be contained in a 333 file racer examples family abox krss lisp 333 initialize the ABox smith family and use the TBox family in abox smith family family 335 Alice is the mother of Betty and Charles instance alice mother related alice betty has child related alice charles has child 335 Betty is mother of Doris and Eve instance betty mother related betty doris has child related betty eve has child 333 Charles is the brother of Betty a
59. sed to delete ABoxes or rename ABoxes as shown in the examples Examples find tbox my ABox Get rid of an ABox i e make the ABox garbage collectible setf find abox abox1 nil 20 Renaming an ABox setf find abox abox2 abox1 abox name function Description Finds the name of the given ABox object Syntax abox name abox Arguments abor ABox object Values ABox name Examples abox name find abox my ABox tbox function Description Gets the associated TBox for an ABox Syntax tbox abox Arguments abor ABox object Values TBox object 5 Knowledge Base Declarations Knowledge base declarations include concept axioms and role declarations for the TBox and the assertions for the ABox The TBox object and the ABox object must exist before the functions for knowledge base declarations can be used The order of axioms and assertions does not matter because forward references can be handled by RACER The macros for knowledge base declarations add the concept axioms and role declarations to the current tbox and the assertions to the current abox 5 1 Built in Concepts top top concept Description The name of most general concept of each TBox the top concept T Syntax top Remarks The concepts top and top are synonyms These concepts are elements of every TBox 21 bottom bottom concept Description The name of the incoherent concept the bottom c
60. sjoint female male implies woman and person some has gender female implies man and person some has gender male equivalent equivalent equivalent equivalent equivalent equivalent equivalent equivalent parent and person some has child person mother and woman parent father and man parent grandmother and mother some has child some has child person aunt and woman some has sibling parent uncle and man some has sibling parent brother and man some has sibling person sister and woman some has sibling person i as gender h as brother has sibling has sister as descendant 4has child Figure 1 Role hierarchy for the family TBox r denotes the internally defined universal role denotes features x denotes transitive roles The RACER Session om eee kp Em Comite Gu woman Figure 2 Concept hierarchy for the family TBox 333 load the TBox CL USER 1 load racer examples family tbox lisp 335 Loading racer examples family tbox lisp T ghee some TBox queries 333 are all uncles brothers CL USER 2 concept subsumes brother uncle T 333 get all super concepts of the concept mother 333 This kind of query yields a list of so called name sets Sa which are lists of equivalent atomic concepts CL USER 3 concept ancestors mother PARENT WOMAN PERSON TOP TOP HUMAN 333 get all sub c
61. tates the disjointness of a set of concepts Syntax disjoint CN CN Arguments CN 1 CN concept names Examples disjoint Yellow Red Blue disjoint January February November December define primitive concept KRSS macro Description Syntax Arguments Remarks Examples Defines a primitive concept define primitive concept CN C CN C concept name concept term C states the necessary conditions for CN define primitive concept Grandmother and Mother Female define primitive concept Father Parent 23 define concept KRSS macro Description Defines a concept Syntax define concept CN C Arguments CN concept name C concept term Remarks Please note that in RACER definitions of a concept do not have to be unique Several definitions may be given for the same concept Examples define concept Grandmother and Mother some has child Parent define disjoint primitive concept KRSS macro Description This axiom states the disjointness of a group of concepts Syntax define disjoint primitive concept CN GNL C Arguments CN concept name GNL group name list which lists all groups to which CN belongs to among other concepts All elements of each group are declared to be disjoint C concept term that is implied by GN Remarks This function is just supplied to be compatible with the KRSS Examples define disjoint primitive concept January Month exactl
62. ts each entry being a list of a concept child of CN and its synonyms Examples taxonomy my TBox may yield Gtop quadrangle tetragon guadrangle tetragon top rectangle diamond rectangle quadrangle tetragon bottom diamond guadrangle tetragon bottom bottom rectangle diamond See also Function atomic concept parents function atomic concept children on page 49 concept synonyms macro Description Returns eguivalent concepts for the specified concept in the given TBox Syntax concept synonyms CN optional thor tbox name current tbox Arguments CN concept name tbox TBox object Values List of concept names Remarks The name CN is not included in the result See also Function concept eguivalent p on page 34 46 atomic concept synonyms function Description Syntax Arguments Values Remarks See also Returns equivalent concepts for the specified concept in the given TBox atomic concept synonyms CN tbox CN tbox concept name TBox object List of concept names The name CN is not included in the result Function concept equivalent p on page 34 concept descendants KRSS macro Description Syntax Arguments Values Remarks Gets all atomic concepts of a TBox which are subsumed by the specified concept concept descendants C optional TBN tbox name current tbox
63. tures from the specified TBox Syntax all features amp optional tbor current tbox Arguments thor TBox Values List of feature terms all transitive roles function Description Returns all transitive roles from the specified TBox Syntax all transitive roles amp optional tbor current tbox Arguments thor TBox object Values List of transitive role terms describe tbox function Description Generates a description for the specified TBox Syntax describe tbox amp optional tbox current tbox stream standard output Arguments thor TBox object or TBox name stream open stream object Values tbox The description is written to stream 53 describe concept function Description Syntax Arguments Values Generates a description for the specified concept used in the specified TBox or in the ABox and its TBox describe concept CN optional tbor or abor current tbox stream standard output tbox or abox TBox object or ABox object CN concept name stream open stream object tbox or abox The description is written to stream describe role function Description Syntax Arguments Values Generates a description for the specified role used in the specified TBox or ABox describe role R optional tbox or abor current tbox stream standard output tbox or abox TBox object or ABox object R role term or feature term stream open stre
64. us constraints temp eve 102 56 temp doris 39 5 gt temp eve temp doris 3 5 ABox Assertions An ABox contains assertions about individuals The set of individual names or individuals for brevity Z is the signature of the ABox The set of individuals must be disjoint to the set of concept names and the set of role names There are two kinds of assertions Concept assertions state that an individual IN is an instance of a specified concept C 11 Role assertions state that an individual IN is a role filler for a role R with respect to an individual IN 9 Attribute assertions state that an object ON is a filler for a role R with respect to an individual IN Constraints state relationships between objects of the concrete domain In RACER the unique name assumption holds this means that all individual names used in an ABox refer to distinct domain objects therefore two names cannot refer to the same domain object Note that the unique name assumption does not hold for object names In the RACER system each ABox refers to a TBox The concept assertions in the ABox are interpreted with respect to the concept axioms given in the referenced TBox The role assertions are also interpreted according to the role declarations stated in that TBox When a new ABox is built the TBox to be referenced must already exist The same TBox may be referred to by several ABoxes If no signature is used for the TBox the assertions in the A
65. ve her a conc pt disjoint p 2 54 nie eek da aa CONCSPE Pee LAN oe BG AE EN Le RME UN EMEA CONCEDES Mi Gal he Ka et ON MS tait Mie te concept is primitive p concept is primitive alc concept coherent Role Queries role subsumes n 22 soa omal ea ma Eau de vooru transitive Pudo K es re douane a bye transitive ek a Maia doh ate ye Bee e Bae feature ps piae iee e pn ta DE eee au amp aca aS feature 15 ce san Beene ee mue ay ee a eb SYMM ETLE DA sats ue ek aos at id a Rue SIMS CRT ah a e nu el a ad ref LexiVerp csata ants Sb ae ede a BR heat op Ge reflexivt ct en ie er eet on ae atomic role inverse TOLE TNVeFSEK 2 4 5 ME enr ALB AR ete nn ine aa TBox Evaluation Functions iii 31 32 32 32 32 32 32 32 33 33 33 34 34 34 39 39 39 39 36 36 36 36 37 37 37 37 38 38 38 38 39 39 39 39 40 40 7 4 7 5 Classify tboX sul ae A ee a e check tbox coherence tbox classifTed P ia fa Ent raie ae Ate thox classified ves ic RUE ok om a oe thox coherentqp mw miku ss pute Bee eu o tbox coherent ABox Evaluation Functions tealize ab hu ele dunes RE A ee H abox nrealized p gt n 22 puhusid s hg AE are a Ge abox realized A Box Queries 2242 es tie Mon Rie ea Be E abox
66. x If satisfiability is to be tested without reference to a TBox nil can be used 32 concept satisfiable p function Description Syntax Arguments Values Remarks Checks if a concept term is satisfiable concept satisfiable p C tbox C concept term tbox TBox object Returns t if C is satisfiable and nil otherwise For testing whether a concept term is satisfiable with respect to a TBox tbox If satisfiability is to be tested without reference to a TBox nil can be used concept subsumes KRSS macro Description Syntax Arguments Values Checks if two concept terms subsume each other concept subsumes C1 C2 amp optional tbox current tbox Ci concept term of the subsumer C concept term of the subsumee tbox TBox object Returns t if C1 subsumes C2 and nil otherwise concept subsumes p function Description Syntax Arguments Values Remarks See also Checks if two concept terms subsume each other concept subsumes p C1 C2 thor C concept term of the subsumer C concept term of the subsumee tbox TBox object Returns t if C1 subsumes C2 and nil otherwise For testing whether a concept term subsumes the other with respect to a TBox tbox If the subsumption relation is to be tested without reference to a TBox nil can be used Function concept equivalent p on page 34 and function atomic concept synonyms on page 47 33 co
67. y 31 has days define disjoint primitive concept February Month and at least 28 has days at most 29 has days 24 add concept axiom function Description This function adds a concept axiom to a TBox Syntax add concept axiom thor C1 C2 amp key inclusion p nil Arguments thor TBox object Ci C2 concept term inclusion p boolean indicating if the concept axiom is an inclusion axiom GCI or an equality axiom The default is to state an inclusion Values tbox Remarks RACER imposes no constraints on the sequence of concept axiom declara tions with add concept axiom i e forward references to atomic concepts for which other concept axioms are added later are supported in RACER add disjointness axiom function Description This function adds a disjointness concept axiom to a TBox Syntax add disjointness axiom thor CN GN Arguments thor TBox object CN concept name GN _ group name Values tbox 5 3 Role Declarations 25 define primitive role KRSS macro with changes Description Syntax Arguments Remarks Examples See also Defines a role define primitive role RN amp key transitive nil feature nil symmetric nil reflexive nil inverse nil domain nil range nil parents nil RN role name transitive if bound to t declares that the new role is transitive feature if bound to t declares that the new role is a feature symmetric if bound to t d
68. y TBox Getting rid of a TBox setf find tbox tbox1 nil Renaming a TBox setf find tbox tbox2 tbox1 tbox name function Description Finds the name of the given TBox object Syntax tbox name thor Arguments thor TBox object Values TBox name 4 2 ABox Management in abox macro Description The ABox with this name is taken or generated and bound to current abox If a TBox is specified the ABox is also initialized Syntax in abox ABN amp optional TBN tbox name current tbox Arguments ABN ABox name TBN name of the TBox to be associated with the ABox Remarks If the specified TBox does not exist an error is signaled Usually this macro is used at top of a file containing an ABox This macro can also be used to create new ABoxes If the ABox is to be continued in another file the TBox must not be specified again 17 Examples See also The specified ABox is the current abox until in abox is called again or the variable current abox is manipulated directly The TBox of the ABox is made the current tbox in abox peanuts characters peanuts instance Schroeder Piano Player Macro signature on page 14 init abox function Description Initializes an existing ABox or generates a new ABox and binds it to the variable current abox During the initialization all assertions and the link to the referenced TBox are deleted Syntax init abox abor optional tbox current tbox
69. y also be forward references to con cepts which will be introduced with define concept or define primitive concept in subsequent axioms The terminology of a RACER TBox may also contain several axioms for a single concept So if a second axiom about the same concept is given it is added and does not overwrite the first axiom 3 3 Role Declarations In contrast to concept axioms role declarations are unique in RACER There exists just one declaration per role name in a knowledge base If a second declaration for a role is given an error is signaled If no signature is specified undeclared roles are assumed to be neither a feature nor a transitive role and they do not have any superroles The set of all roles R includes the set of features F and the set of transitive roles R The sets F and R are disjoint All roles in a TBox may also be arranged in a role hierarchy The inverse of a role name RN can be either explicitly declared via the keyword inverse e g see the description of define primitive role in Section 5 3 page 25 or referred to as inv RN Features also called attributes restrict a role to be a functional role e g each individual can only have up to one filler for this role Transitive Roles are transitively closed roles If two pairs of individuals JN and IN2 and IN and IN3 are related via a transitive role then JN and IN3 are also related via R Role Hierarchies define super and subrole relatio
70. y related via the specified role individuals related IN IN2 R koptional abox current abox IN individual name of the predecessor IN individual name of the role filler R role term abor ABox object Returns t if IN is related to IN via R in abox and nil otherwise individuals related p function Description Syntax Arguments Values See also Checks if two individuals are directly related via the specified role individuals related p IN IN2 R abox IN individual name of the predecessor IN individual name of the role filler R role term abor ABox object Returns t if JN is related to IN via R in abox and nil otherwise Function retrieve individual filled roles on page 57 Function retrieve related individuals on page 56 44 individual equal KRSS macro Description Checks if two individual names refer to the same domain object Syntax individual equal IN IN2 optional abor current abox Arguments IN IN individual name abor abox object Remarks Because the unique name assumption holds in RACER this macro always returns nil for individuals with different names This macro is just supplied to be compatible with the KRSS individual not equal KRSS macro Description Checks if two individual names do not refer to the same domain object Syntax individual not equal IN IN amp optional abor current abox Arguments IN IN
71. yntax add concept assertion abor IN C Arguments abor ABox object IN individual name C concept term Values abox Examples add concept assertion find abox peanuts characters Lucy Person add concept assertion find abox peanuts characters Snoopy and Dog Cartoon Character forget concept assertion function Description Syntax Arguments Values Remarks Examples Retracts a concept assertion from an ABox forget concept assertion abos IN C abor ABox object IN individual name C concept term abox For answering subsequent queries the index structures for the ABox will be recomputed i e some queries might take some time e g those queries that require the realization of the ABox forget concept assertion find abox peanuts characters Lucy Person forget concept assertion find abox peanuts characters Snoopy and Dog Cartoon Character 29 related KRSS macro Description Syntax Arguments Builds a role assertion asserts that two individuals are related via a role or feature related IN IN R IN individual name of the predecessor IN individual name of the filler R arole term or a feature term Examples related Charlie Brown Snoopy has pet related Linus Lucy inv has brother add role assertion function Description Adds a role assertion to an ABox Syntax add role assertion abor IN IN

RACER User's Guide and Reference Manual Version 1.6

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