- From: Dan Brickley <danbri@w3.org>
- Date: Fri, 1 Aug 2003 20:48:14 -0400
- To: w3c-rdfcore-wg@w3.org
An excellent question on RDF IG list. Can anyone here provide an authoritative answer? WebOnt WG members? Dan ----- Forwarded message from David Menendez <zednenem@psualum.com> ----- From: David Menendez <zednenem@psualum.com> Date: Fri, 1 Aug 2003 15:43:18 -0400 To: www-rdf-interest@w3.org Subject: Can an owl:Class subclass an rdfs:Class? Message-ID: <r02000000-1026-E085EBD6C46111D78E90000393758032@[10.0.1.2]> Resent-From: www-rdf-interest@w3.org Resent-Date: Fri, 1 Aug 2003 16:49:33 -0400 (EDT) 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/> ----- End forwarded message -----
Received on Friday, 1 August 2003 20:48:14 UTC