RE: NEWBIE: Property restriction semantics

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