subClassOf from Jos de Bruijn on 2005-10-12 (public-webont-comments@w3.org from October 2005) (original) (raw)

Hi Alan, all,

Can someone please clarify this for me.

In Section 3.2.1 of OWL Web Ontology Lang Ref, it mentioned that The rdfs:subClassOf construct is defined as part of RDF Schema. Its meaning in OWL is exactly the same ..... However, RDFS semantic conditions table in Section 4.1 of RDF Semantics defines rdfs:subClassOf to be an "if ... then ... " relationship, whereas the If-and-only-if conditions table in Section 5.2 of OWL Semantics and Abstract Syntax defines rdfs:subClassOf to be "iff"

From the definition, it seems that OWL defines subclass relationship stronger than RDFS does. My intuitive understanding (please correct me if I am wrong) is that, in OWL, if the class extension of c1 is a subset of class extension of c2, then c1 is subClassOf c2.

You are completely right. The subclass relationship in OWL is indeed stronger than the subclass relationship in RDFS. I guess this is a mistake in the OWL Reference document (I'm CCing public-webont-comments, hoping this mistake will be rectified in the errata).

The authors of the OWL reference document may have been misled by the informative section 4.2 of the RDF semantics document [1] which describes a possible extension of the RDFS semantics to include the if-and-only-if definitions which are in OWL.

Best, Jos

[1] http://www.w3.org/TR/rdf-mt/

I am not trying to be picky about the wording here. Just try to understand this better.

Thanks,

Zhe (Alan) Wu Oracle

Jos de Bruijn, http://www.uibk.ac.at/~c703239/ +43 512 507 6475 jos.debruijn@deri.org

DERI http://www.deri.org/

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