1. Extensible Ontological Modeling Framework for Subject Mediation L. A. Kalinichenko, N. A. Skvortsov Institute for Problems of Informatics, RAS {leonidk,scvora}@synth.ipi.ac.ru http://www.ipi.ac.ru/synth/ RCDL’2002, Dubna

2. Outline An approach for the ontological model mapping in a subject mediation environment intended for heterogeneous information sources integration in a particular subject domain is considered. Such mapping is needed for an information source registration at the mediator. It is assumed that such sources apply the DAML+OIL ontological model. A mediator ontological language (MOL) may depend on a subject domain and is to be defined at the mediator consolidation phase. Principles of information resource registration. Ontological framework of subject mediators. Mapping of DAML+OIL elements into MOL ones. Reverse mapping

3. Registration of resources in subject mediator Canonical model of the the mediator used for information resource specifications Mediators work in consolidation phase, then in operational phase Specification modules: schemas, concept definitions, vocabularies Local as View (LAV) mediator architecture is assumed as a basis for the subject mediation For this purpose source specifications are mapped to federative level of mediator specifications

4. Mediator’s Ontological Framework the same canonical model used for specifications of ontological contexts of mediator and of information sources Elements of specifications are concepts, attributes, associations, invariants Also semantic relationships that may be fuzzy To contextualize information sources at the mediator during their registration, it is required to map local ontological contexts of the sources into the mediator’s ontology. loose ontological integration provides for establishing fuzzy correlation between related concepts tight ontological integration consists in composition of ontological modules using complete specifications of concepts as type definitions

5. DAML+OIL DAML+OIL layered on top of RDFS Classes (concepts) and properties (roles) DAML+ OIL ontology consists of set of axioms asserting characteristics of classes and properties Equivalent to very expressive description logic SHIQ Reasoning algorithms for satisfiability and subsumption (it may be used for tight ontology integration) DAML+OIL has been submitted to W3C as a candidate for the Web ontology language Class constructors: intersectionOf, unionOf, complementOf, oneOf, toClass, hasClass, hasValue, minCardinalityQ, maxCardinalityQ, cardinalityQ Axioms: subClassOf, sameClassAs, subPropertyOf, samePropertyAs, sameIndividualAs, disjointWith, differentIndividualFrom, inverseOf

6. Core of the Mediator Ontology Language (1) Types (concepts) Attributes Invariants {Animal; in: type, daml_oil; hasMother: Female; metaslot in: HasMother; end sameAs: {in: invariant, samePropertyAs, {{ all a/Animal ( hasMother(a) = HasMom(a) }}} }

7. Core of the Mediator Ontology Language (2) Association types {HasFather; in: metatype, association, daml_oil; instance_section: {domain: Animal; range: Male; association_type: {{1,1},{0,inf}}; metaslot in: onProperty, cardinality, UniqueProperty, end} };

8. MOL core extension equivalent to DAML+OIL (1) Need in new metaclasses daml_oil: types and associations become instances of the metatype; restriction: belonging to it are restrictions of DAML+OIL; disjointWith, disjointUnionOf, onProperty, toClass, hasValue, hasClass, cardinality, maxCardinality, minCardinality, cardinalityQ, maxCardinalityQ, minCardinalityQ, sameTypeAs, equivalentTo, samePropertyAs: metatypes to which invariants in type definitions can be associated. These invariants interpret respective DAML+OIL elements.

9. MOL core extension equivalent to DAML+OIL (2) Class Elements Interpretation I:{in: invariant, disjointWith, {{(C>T1 & CE>T2 = {}) }}} I:{in:predicate, invariant, disjointUnionOf, {{(C>T = (CE1>T1 | CE2>T2)) & (CE1>T1 & CE2>T2 = {}) }}} I:{in: invariant, sameClassAs, {{(C>T1 = CE>T2)}}} {HumanBeing; in: type, daml_oil; supertype: Person; sameTypeAs: {in: invariant, sameClassAs {{all p/Person (HumanBeing(p) = Person(p)) }}} };

10. MOL core extension equivalent to DAML+OIL (3) Property Restrictions Interpretation I:{in: invariant, onProperty, toClass, {{all x (ST(x) & (P(x)  CE>T))}}} I:{in: invariant, onProperty, hasValue, {{all x (ST(x) & yP(x)) }}} I:{in: invariant, onProperty, hasClass, {{all x (ST(x) & ex y (P(x,y) & CE>T(y))) }}} {R_Person; in: type, daml_oil, restriction; supertype: Animal; hp: {in: invariant, onProperty, toClass, {{all ap (R_Person(ap) & hasParent(ap) <= Person) }}}; };

11. MOL core extension equivalent to DAML+OIL (4) Cardinality Constraints Interpretation daml:cardinality -> association_type: {{N,N},{?,?}} daml:maxCardinality -> association_type: {{0,N},{?,?}} daml:minCardinality -> association_type: {{N,inf},{?,?}} {domain: C>T1; range: CE>T2; association_type: {{N,N},{?,?}}; metaslot in: onProperty, cardinalityQ end } or I:{in: invariant, onProperty, cardinalityQ, {{all x(C>T1(x) & count (P(x) & CE>T2) = N) }}}

12. Reverse Mapping of the MOL into DAML+OIL The mapping is reversible Semantics of any DAML+OIL definition mapped to MOL is retrievable using newly defined metaclasses DAML+OIL specifications are extended by RDF namespace to save semantics of fuzzy semantic relationships in MOL {Female; in: type, daml_oil; supertype: Animal; disjoint: {in: invariant, disjointWith, {{Male(a/Animal) & Female(a/Animal) = {} }}} };

13. Conclusion Compatibility to most popular ontologies and probable W3C recommendation for Web ontologies Results may be used for mapping other ontologies SHIQ reasoning algorithms are helpful for tight ontology integration