- From: pat hayes <phayes@ai.uwf.edu>
- Date: Mon, 26 Aug 2002 00:35:48 -0700
- To: Piotr Kaminski <piotr@ideanest.com>
- Cc: www-rdf-comments@w3.org
>A minor nitpick: > >From: "pat hayes" <phayes@ai.uwf.edu> >> What makes something a class is just that it has some >> things in it (that is, in its extension) > >A class can have an empty extension. If I say: > >pk:EmptyClass rdf:type rdfs:Class > >And there are no statements like this anywhere in my model: > >_:anything rdf:type pk:EmptyClass > >Then pk:EmptyClass still qualifies as a class, right? > >So I think it's more accurate (and perhaps simpler?) to say, just like in >the Model Theory: > >A resource is a class if and only if it has rdf:type rdfs:Class (implicitly >or explicitly). >Every resource that is the object of an rdf:type statement is implicitly of >rdf:type rdfs:Class. >Any resource can be a class (implicitly, explicitly, or both). > >Of course, to make a coherent picture with extensions of rdfs:Class, we need >to say that rdfs:subClassOf is transitive, etc. But I think the rules above >make a solid foundation for newcomers. Yes, you are absolutely correct. I forgot about empty classes. Sorry if my email was misleading. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
Received on Monday, 26 August 2002 13:32:52 UTC