- From: Dimitrios A. Koutsomitropoulos <kotsomit@hpclab.ceid.upatras.gr>
- Date: Tue, 17 Feb 2004 19:27:09 +0200
- To: "'Peter F. Patel-Schneider'" <pfps@research.bell-labs.com>
- Cc: <public-webont-comments@w3.org>
Thanks indeed! It seems more clear now. However... > -----Original Message----- > From: public-webont-comments-request@w3.org > [mailto:public-webont-comments-request@w3.org] On Behalf Of > Peter F. Patel-Schneider > Sent: Tuesday, February 17, 2004 5:49 PM > To: kotsomit@hpclab.ceid.upatras.gr > Cc: public-webont-comments@w3.org > Subject: Re: NEWBIE: Property restriction semantics > > > From: "Dimitrios A. Koutsomitropoulos" > <kotsomit@hpclab.ceid.upatras.gr> > Subject: Re: NEWBIE: Property restriction semantics > Date: Tue, 17 Feb 2004 17:26:09 +0200 > > > > > > > Let's consider the following modification of Brian's example: > > > > > > <owl:Class rdf:ID="Student"/> > > > > <owl:ObjectProperty rdf:ID="hasGrade"> <rdfs:domain > > rdf:resource="#Student"/> <rdfs:range rdf:resource="#Grade"/> > > </owl:ObjectProperty> > > > > <owl:Class rdf:ID="FailedStudent"> > > <rdfs:subClassOf rdf:resource="#Student"/> <owl:equivalentClass> > > <!-- instead of subClassOf --> > > <owl:Restriction> > > </owl:onProperty rdf:resource="#hasGrade"/> > > </owl:hasValue rdf:resource="#Failed"/> > > </owl:Restriction> > > </owl:subClassOf> > > </owl:Class> > > > > And just assert that Brian isA FailedStudent: > > > > <FailedStudent rdf:ID="Brian" /> > > > > Would this imply that Brian hasGrade Failed? ...by "Brian hasGrade Failed" I do not mean that "Brian in hasGrade:Failed" which I can understand. I mean if the actual role filler for instance:Brian and Role:hasGrade will be the instance:Failed. For example, Racer does not seem to infer this... > > Yes. Note, however, that this inference would also be valid > in the original example. Note also that your example doesn't > make much sense, as it has lots of unusual consequences. > > This is yet another case where the RDF/XML syntax is not > helpful, as it obscures the real semantic relationships. > What you have done is define FailedStudent as follows > > > FailedStudent <= Student > FailedStudent = hasGrade : Failed > > >From this you can infer > > hasGrade:Failed <= Student > > i.e., any thing that has a failing grade (perhaps in love, > for example) would be a Student. What you probably want is > > FailedStudent = Student & hasGrade:Failed > > or > > FailedStudent <= Student & hasGrade:Failed > > In both these cases > > Brian in FailedStudent > > implies > > Brian in hasGrade:Failed > > > > I would be really happy for any feedback on this! > > > > Many thanks, > > > > > > Dimitris Koutsomitropoulos > > Peter F. Patel-Schneider > >
Received on Tuesday, 17 February 2004 12:27:03 UTC