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Re: Can an owl:Class subclass an rdfs:Class?

From: Francesco CannistrÓ <fracan@inwind.it>
Date: Sat, 2 Aug 2003 11:02:04 +0200
Message-ID: <019f01c358d4$bf647a10$6a941d97@Matrix>
To: "David Menendez" <zednenem@psualum.com>, <www-rdf-interest@w3.org>

Maybe you overcome the problem by explicitly asserting that #Person is of
type owl:Class, ie:

<owl:Class rdf:about="http://xmlns.com/foaf/0.1/Person"/>
<owl:Class rdf:about="http://example.com/ex/Actor">
     <rdfs:isDefinedBy rdf:resource="http://example.com/ex"/>
     <rdfs:subClassOf rdf:resource="http://xmlns.com/foaf/0.1/Person"/>

I don't think this would create any interoperability problem.
How does this solution sounds to you?


----- Original Message -----
From: "David Menendez" <zednenem@psualum.com>
To: <www-rdf-interest@w3.org>
Sent: Friday, August 01, 2003 9:43 PM
Subject: Can an owl:Class subclass an rdfs:Class?

> I think I have a handle on the distinction between owl:Class and
> rdfs:Class, but I'm uncertain about when or whether OWL Ontologies can
> refer to rdfs:Classes.
> For example, an ontology for describing entertainment figures might need
> a class like ex:Actor and it might try to leverage the wide acceptance
> of FOAF by declaring ex:Actor a subclass of foaf:Person. My question is,
> can it?
> Once all the imports statements are resolved we end up with something
> like this:
>   <rdfs:Class rdf:about="http://xmlns.com/foaf/0.1/Person">
>     <rdfs:isDefinedBy rdf:resource="http://xmlns.com/foaf/0.1/"/>
>   </rdfs:Class>
>   <owl:Class rdf:about="http://example.com/ex/Actor">
>     <rdfs:isDefinedBy rdf:resource="http://example.com/ex"/>
>     <rdfs:subClassOf rdf:resource="http://xmlns.com/foaf/0.1/Person"/>
>   </owl:Class>
> This is allowed in OWL Full, but as far as I can tell, it isn't allowed
> in OWL Lite or OWL DL. My question then is, why not? I understand that
> OWL needs to keep classes, properties, and individuals distinct, but I
> can't quite see what specific problem is raised here. In RDF-MT above
> fragment is interpreted as "any instance of ex:Actor is also an instance
> of foaf:Person". Even if foaf:Person had strange applications that made
> it unsuitable to be expressed as an owl:Class, those wouldn't seem to
> affect ex:Actor.
> Assuming I understand this correctly, the effect is that vocabularies
> defined OWL DL and OWL Lite can't build on existing terms in the web.
> Naturally, similar questions exist for sub-properties, domains, and
> ranges.
> If it turns out that OWL Lite and OWL DL cannot reference RDFS
> vocabularies (as I suspect they do), would something like this be
> reasonable?
> File 1
> ------
>     <owl:Ontology rdf:about="http://example.com/ex/core">
>       <rdfs:label>Entertainer Ontology (OWL Lite version)</rdfs:label>
>       <rdfs:seeAlso rdf:resource="http://example.com/ex/full"/>
>     </owl:Ontology>
>     <owl:Class rdf:about="http://example.com/ex/Actor">
>       <rdfs:isDefinedBy rdf:resource="http://example.com/ex/core"/>
>     </owl:Class>
> File 2
> ------
>     <owl:Ontology rdf:about="http://example.com/ex/full">
>       <rdfs:label>Entertainer Ontology (OWL Full version)</rdfs:label>
>       <owl:imports rdf:resource="http://example.com/ex/core"/>
>       <owl:imports rdf:resource="http://xmlns.com/foaf/0.1/"/>
>     </owl:Ontology>
>     <owl:Class rdf:about="Actor">
>       <rdfs:subClassOf rdf:resource="http://xmlns.com/foaf/0.1/Person"/>
>     </owl:Class>
> --
> David Menendez <zednenem@psualum.com> <http://www.eyrie.org/~zednenem/>
Received on Saturday, 2 August 2003 05:02:41 UTC

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