- From: Frank Manola <fmanola@acm.org>
- Date: 2008年8月14日 11:15:53 -0400
- To: Michael Schneider <schneid@fzi.de>
- Cc: "SWIG" <semantic-web@w3.org>, "Richard H. McCullough" <rhm@PioneerCA.com>
- Message-Id: <A5E94CB7-A35D-4E4C-A591-6D7E3CA91694@acm.org>
On Aug 13, 2008, at 7:57 PM, Michael Schneider wrote: > Hi Frank! > > Frank Manola wrote: > >> There aren't any classes in RDF (per se); in RDFS there are classes, >> and they can be treated as individuals (which is where we came in, >> more or less). > > As a minor remark, I think it's easier to understand the situation of > classes in RDFS, if one states the above sentence the other way > around: In > RDFS there are individuals (aka resources), and some of them can be > treated > as classes, namely those which happen to have a class extension > associated > with them. Analog, some individuals have a property extension > associated > with them, and are therefore properties. An individual may even act > as both, > a class *and* a property, if it has both a class extension and a > property > extension associated. But in any case (as you say), all classes and > properties are individuals, which exist in the RDFS universe, i.e. the > domain of discourse. Michael-- You may be right about the sentence "direction". My main point was simply that, strictly speaking, the "class" concept isn't part of RDF (it isn't in the "rdf:" vocabulary); classes are only introduced when you get to the "rdfs:" vocabulary, as a "semantic extension". --Frank > > >> That is, in RDFS a class is a resource (like >> everything else that can be referred to in RDFS), and resources can >> be >> the subjects of triples. >> >> --Frank > > Cheers, > Michael >
Received on Thursday, 14 August 2008 15:16:44 UTC