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/ ---------------------------------------------- An expert is a person who has made all the mistakes that can be made in a very narrow field. - Niels BohrReceived on Wednesday, 12 October 2005 08:47:31 UTC
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