1 / 28

An Extensible Approach for Modeling Ontologies in RDF(S)

An Extensible Approach for Modeling Ontologies in RDF(S). Steffen Staab, Michael Erdmann, Alexander Mädche, & Stefan Decker Research Group Knowledge Management Institute AIFB, University of Karlsruhe, & DB Group, Stanford University Lisbon, September 21, 2000. RDF(S). What is an Ontology?.

cyndi
Download Presentation

An Extensible Approach for Modeling Ontologies in RDF(S)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Extensible Approach for Modeling Ontologies in RDF(S) Steffen Staab, Michael Erdmann, Alexander Mädche, & Stefan DeckerResearch Group Knowledge Management Institute AIFB, University of Karlsruhe, & DB Group, Stanford UniversityLisbon, September 21, 2000

  2. RDF(S) What is an Ontology? • Light-weight Ontology • concepts, atomic types • is-a hierarchy among concepts • associations between concepts • Heavy-weight Ontology • cardinality constraints • taxonomy of relations • reified statements • Axioms / semantic entailments of various tastes • expressiveness (DL, propositional, horn, or first order logic, higher order) • inferences

  3. Tools for Ontologies • Light-weight • uncontroversial • all Tools support light-weight • Protege, Stanford • OntoEdit, Karlsruhe • UML-Tools, several • Heavy-weight • no consensus yet • layering seems appropriate/necessary

  4. Concepts, Relations, ....

  5. The use of XML Namespaces in RDF(S) • Distinguish between different modeling layers • Reuse and integrate existing schemata and applications • XML serialization of RDF(S)

  6. Odoc & O • Odoc: namespace for ontology documentation • O: namespace for modeling of ontological axioms • An actual ontology definition – http://ontoserver.aifb.uni-karlsruhe.de/schema/example.rdf

  7. Modeling ontology metadata using RDF Dublin Core • Dublin Core Metadata element set comprises 15 elements ensuring a maximal level of generality and exchangeability. • Extention of Dublin Core http://ontoserver.aifb.uni-karlsruhe.de/schema/ontodoc

  8. <?xml version=‘1.0’ encoding =‘ISO-8859-1’?> <rdf:RDF xmlns: rdf = http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:dc = http://purl.oclc.org/dc xmlns:odoc=“http://ontoserver.aifb.uni-karlsruhe.de/schema/ontodoc”> <rdf: Description about = “”> <dc: Title>an Example Ontology</dc:Title> <dc:creator> <rdf: Bag> <rdf:li>Steffen Staab</rdf:li> … </rdf:Bag> </dc:creator> <dc:date>… <dc:format>… <dc:description>… <dc:subject>….. <odoc:url> http://ontoserver.aifb.uni-karlsruhe.de/schema/example.rdf </odoc:url> <odoc:version>2.1</odoc:version> <odoc:last_modification>2000-03-01</odoc:last_modification> <odoc:ka_technique>semi-automatic text knowledge accquisition</odoc:ka_technique> <odoc:ontology_type>domain ontology</odoc:ontology_type> <odoc:no_concepts>24</ odoc:no_concepts > <odoc:no_relations>23</ odoc:no_relations > <odoc:no_axioms>11</ odoc:no_axioms > <odoc:highest_depth_level>6</odoc:highest_depth_level> </rdf:Description> </rdf:RDF> Example

  9. Modeling Ideal Modeling (WYMIWYG) • Modeling not constrained by any language • All appropriate epistemological primitives and modeling styles should be usable Real Modeling • A particular language always restricts allowed primitives (modeling language) • A particular language is needed in applications(application language) => distinguish modeling language from final application language translate automatically

  10. Axioms • For Semantic Web and DAML more than light-weight is needed! • Axioms • Framework for conceptual modeling of axioms • Ontology of axiom patterns • language specific axiom-schemata can work with that knowledge • Interoperability is an issue • RDF / RDFS seem appropriate next slide next but one slide

  11. Axiom Patterns • 1. Axioms for a relational algebra • (a) Reflexivity of relations • (b) Symmetry of relations • (c) Asymmetry of relations • (d) Transitivity of relations • (e) Inverse relations • (f) Irreflexivity of relations • (g) Antisymmetry of relations • 2. Composition of relations • 3. (Exhaustive) Partitions of Concepts

  12. Axiom Patterns • 4. Axioms for subrelation relationships • 5. Axioms for part-whole reasoning [Winston 87] [Chaffin 92] • PhysicalPartOf • MemberOf • PortionOf • PhaseOf • FeatureOf • SubRegionOf • 6. Nonmonotonicity • 7. Axioms for temporal and modal contexts • 8. (General axioms (application specific, ad hoc))

  13. A simple symmetry example. • A relation MarriedWith(such as used for “William is married with Susan”) • First-order predicate logic: MarriedWith(X,Y)MarriedWith(Y,X)

  14. A simple symmetry example. • In F-Logic Person:LivingBeing[MarriedWithPerson]. Man::Person. • William:Man[MarriedWithSusan] • A rule corresponding to 1 is given by 4 Y[MarriedWithX]  X[MarriedWithY]

  15. A simple symmetry example. • We denote symmetry as predicate that holds for particular relations: Symmetric(MarriedWith) • In RDF(S) this specification may easily be realized by a newly agreed upon class o:Symmetric <o:Symmetric rdf:ID=“marriedWith”/> • Derive the implications of symmetry by a general rule Y [RX]Symmetric(R) and X[RY]

  16. subClassOf rdfs:Resource instanceOf RDF/RDFSlayer and namespace rdfs:Class rdf:Property o:Partition o:Relation o:Composition o:Partonomic- RolePropagation ontology meta layerand namespace o:isInverseRelationOf o:PartOfRel o:Asymmetric o:Reflexive o:Transitive o:Irreflexive o:Symmetric appl:Organisation o:secondComponent o:firstComponent appl:Person o:composee Application-specific schema and namespace appl:Man appl:Woman appl:fatherInLaw appl:fatherOf appl:marriedWith appl:marriedWith Application- specificactual data http://www.foo.com/W.Smith http://www.foo.com/S.Smith appl:lastName appl:lastName appl:firstName appl:firstName William Smith Susan Smith

  17. Example of Composition of Relations <o:Composition rdf:ID="FatherInLawComp"> <o:composee rdf:Resource="fatherInLawOf"/> <o:firstComponent rdf:Resource="fatherOf"/> <o:secondComponent rdf:Resource="marriedWith"/> </o:Composition> rdf:Class rdfs:Property o:Composition o:Relation Composition(fatherInLawOf, fatherOf, marriedWith). o:IrreflexiveRel forall R,Q,S,X,Y,Z X[R ->> Z] <- Composition(R, Q, S) and X[Q ->> Y] and Y[S ->> Z]. o:secondComponent o:composee appl:marriedWith o:firstComponent forall X,Y,Z X[fatherInLawOf ->> Z] <- X[fatherOf ->> Y] and Y[marriedWith ->> Z]. appl:fatherInLawOf appl:fatherOf

  18. General Axioms • Two ways to approach • RDF(S) representation for a particular inferencing system • OIL • Representation that is more application specific • A practical choice for many application-specific axioms

  19. OntoEdit supports Axiom Classification fatherInLawOf fatherOf marriedWith

  20. Ontology Engineering using OntoEdit • Interaction with the user on a conceptual level • Multiple views for concepts, relations and axioms • Multilinguality • Linkable to NLP domain lexicon • Exports ontology (incl. axioms) into several formats • F-Logic (main language) • RDF/RDFS • DTDs (as far as possible) • ORDB-Schema (as far as possible) • OIL (partially and in RDF) • UML/XMI (planned) • the DAML language (when specified ;-)

  21. Ontoedit

  22. Frame-Logic Inference Engine Access Automatically Derived from Axiom views Pure F-Logic Debugging Instances + Rule Debugging

  23. FaCT DL Engine Interface • Generate FaCT LISP KB (future: OIL) • Call FaCT Client, transform ontology on FaCT server • Ask server

  24. RDF/RDFS layer and namespace rdfs:Resource subClassOf instanceOf rdfs:Property rdf:Class rdfs:ConstraintProperty rdf:type rdfs:subClassOf rdfs:subPropertyOf rdfs:domain rdfs:range XRDF OIL DAML o:isInverseRelationOf o:Relation o:Composition o:PartOfRel o:ReflexiveRel o:Partition o:IrreflexiveRel Ontological meta layer for kinds of relations with own namespace o:PhysicalPartOfRel o:SymmetricRel o:AsymmetricRel o:MemberOfRel o:TransitiveRel o:SubRegionOfRel Application Flexible Epistemological Level XRDF OIL DAML

  25. Conclusion • ‘‘No Method fits all‘‘ • Different applications need • different representation languages • with their underlying reasoning services • Ontology development must be aware of this • conceptual modeling • mechanisms to access/integrate several ontologies • distributed on the web • identified by (XML-) namespaces

  26. Thank You!

More Related