Tools for Developing and Using DAML-Based Ontologies and Documents

1. Tools for Developing and Using DAML-Based Ontologies and Documents Richard Fikes Deborah McGuinness Sheila McIlraith Jessica Jenkins Son Cao Tran Gleb Frank Scott Sanner Honglei Zeng Knowledge Systems Laboratory, Computer Science Department, Stanford University The Chimaera Ontology Tool Suite A Knowledge Evolution Environment Axiomatic Semantics for DAML+OIL, RDFS, and RDF • Formal specification of intended meaning • Translates DAML+OIL and RDF into first order logic (FOL) • Produces a logically equivalent ontology in FOL • Facilitates query answering and constraint checking • By traditional theorem provers and problem solvers • Provides specs for special purpose reasoners • Translation method – • Translate DAML+OIL descriptions into RDF statements I.e., into “Property P of resource R has value V” • Translate each RDF statement into an FOL sentence I.e., into “(PropertyValue P S O)” • Simplify property typing sentences using relation type I.e., simplify “(PropertyValue type S O)” to “(type S O)” • Add axioms from the semantics document • Example – • DAML+OIL description of class Person and person Joe • <rdfs:Class rdf:ID = "Person"> • <rdfs:subClassOf rdf:resource = "#Animal” /> • <restrictedBy> • <Restriction> • <onProperty resource = "#parent” /> • <toClass resource = "#Person” /> • </Restriction> • </restrictedBy> • </Class> • <Person ID = "Joe"> • <parent resource = "#John” /> • </Person> • Translation into RDF statements: • (type Class Person) • (subClassOf Person Animal) • (type Restriction R) • (restrictedBy Person R) • (onProperty R parent) • (toClass R Person) • (type Joe Person) • (parent Joe John) • Translation into first order logic: • (Type Class Person) • (PropertyValue subClassOf Person Animal) • (Type Restriction R) • (PropertyValue restrictedBy Person R) • (PropertyValue onProperty R parent) • (PropertyValue toClass R Person) • (Type Joe Person) • (PropertyValue Parent Joe John) • Primary axiom for toClass– • “If object R is a value of restrictedBy for object C1, object P is a value of onProperty for R, and object C2 is a value of toClass for R, then for all objects I and V, if I is of type C1 and V is a value of P for I, then V is type C2.” • (=> (and (PropertyValue restrictedBy ?c1 ?r) • (PropertyValue onProperty ?r ?p) • (PropertyValue toClass ?r ?c2)) • (forall (?i ?v) (=> (and (Type ?i ?c1) • (PropertyValue ?p ?i ?v)) • (Type ?v ?c2)))) • Is John a Person? • Use axiom to infer – • (forall (?i ?v) (=> (and (Type ?i Person) • (PropertyValue parent ?i ?v)) • (Type ?v Person))) • And then infer – • (Type John Person) • “Yes”, John is a Person. • Tools for ontology diagnosis and merging • Available as a Web service • Usable from a Web browser • Online user manual, tutorial, and demonstration movie • www.ksl.stanford.edu/software/chimaera • Performs ontology diagnostics in batch mode • Uploads and analyzes user’s ontology • Accepts KBs in DAML+OIL, DAML-ONT, RDF, XML, KIF, OKBC, … • Provides results as HTML pages linked to frames and axioms • Provides user selectable set of diagnostic tests • Analyzes both the structure and content of an ontology • Uses reasoners to analyze content • Currently runs 28 diagnostic tests • Is an OKBC client that runs with any OKBC server • OKBC – Open Knowledge Base Connectivity • We use our Ontolingua OKBC knowledge server • Ontology editor supports – • Editing object-oriented descriptions (frames) • Inclusion of ontologies from any Web sites • Ontology browser shows – • Frames with inherited values and constraints • Ontology inclusion structure • Class-subclass taxonomy • Uses our JTP theorem prover to perform reasoning tests • Enables heterogeneous reasoners to interoperate • Contains general purpose theorem prover • Uses Model Elimination reasoning method • Contains special purpose reasoners for ontology descriptions • Being customized for DAML+OIL • Reports – • Errors • Logical inconsistencies E.g., contradictory type and cardinality constraints object an instance of disjoint classes • Content structure errors E.g., terms used but not defined • Anomalies • Missing information E.g., No type constraints on property Class contains no local information • Redundancies E.g., Redundant superclass and type links • Extraneous structure or content E.g., Terms defined but not used • Irregularities E.g., Cyclic subclass links Class with a single subclass Object an instance of a non-leaf class • Summaries E.g., Counts of term references • Suggestions E.g., Use consistent naming conventions Include disjointness constraints • Next steps in our development of Chimaera • Provide interactive follow-up to diagnostics • Identify KB content on which diagnosis result is based • Suggest repairs or repair strategies; provide user guidance through repair • Reasoning tests that may take substantial time • Performed in background • Results incrementally posted on Web page • Result summaries sent to user via e-mail when ready • Extend for greater scalability