Web Ontology Language

Created on March 11, 2013, 4:07 p.m. by Hevok & updated by Hevok on May 2, 2013, 5:32 p.m.

The Semantic Web Ontology Language (OWL) is the Semantic Web Version of the Description Logic SHROIQ(D) which has a special Language and Syntax, but its Semantics in the end comes to the Description Logics.

The Web Ontology Language depends or corresponds to a Description Logics. The two different version of OWL, OWL 1 and OWL2 depend on different Description Logics. OWL 1 on SHOIN(D) and OWL 2 on SHROIQ(D)

With OWL one defines Ontologies. An OWL Ontology consists out of Classes, Properties and Individuals. Individuals are Instances of Classes. A Property corresponds to a Role in Description Logics.

In general in OWL as well as in Description Logics, the Open World Assumption holds, which means that the absence of Information must not be evaluated as negative Information.

Also for OWL the Unique Name Assumption does not hold. This means that differences between Entities and Classes must be expressed explicitly. For example Person A may denote the same Person as Person B.

So if two persons or two Instances really are different, then one has to express this in an explicit way.

  • OWL (SHOIN(D)) - W3C Recommendation since 2004
  • OWL 2 (SHROIQ(D)) - W3C Recommendation since 2009

  • OWL Ontology consists of

  • Open World Assumption

    • "Absence of Information must not be valued as negative Information."
    • E.g. sitsNextTo(PersonA, PersonB)

    PersonA may also sit next to anohter person... * No Unique Name Assumption - "Difference must be expressed explicitly" + E.g. PersonA possibly denotes the same Individual as PersonB


Tags: logic, property, predicate, relation
Categories: Concept
Parent: Description Logics
Children: OWL 1, OWL Building Blocks, OWL Class, OWL Syntax Variant, Properties, Structure of OWL

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