- From: patrick hayes <phayes@ai.uwf.edu>
- Date: Thu, 30 May 2002 11:10:15 -0500
- To: Dan Connolly <connolly@w3.org>
- Cc: danbri@w3.org, bwm@hplb.hpl.hp.com, www-rdf-comments@w3.org, em@w3.org, w3c-semweb-cg@w3.org, pfps@research.bell-labs.com
>On Thu, 2002-05-30 at 10:26, Peter F. Patel-Schneider wrote: >[...] >> I'm only interested in relationships between RDF graphs. Which such >> relationships are RDF relationships? >> >> My view is that the only such relationships are RDF entailment and RDFS >> entailment. Any agent that computes any other relationship between RDF >> graphs is not doing RDF. > >Why is RDFS special? It's just the first of many RDF vocabularies, >no? Its more than just an RDF vocabulary because it has some extra semantic conditions. For example, if RDFS is considered purely as an RDF vocabulary, then rdfs:subClassOf is not required to be transitive; in fact, there is no way to express transitivity of a property in RDF. Considered as RDFS, however, it is required to be transitive. The distinction is made exact in the MT document by distinguishing between RDF-entailment and RDFS-entailment. In general, if a particular vocabulary has some extra semantic conditions attached to it, then there will be a new notion of entailment (I used the generic term 'vocabulary entailment' for this idea in the MT document: http://www.w3.org/TR/rdf-mt/#NameSpaceEntailment ). Most RDF vocabularies, eg dublin core, RSS, have no extra semantics attached to them. DAML+OIL certainly does, of course, but then I wouldn't even call that an RDF vocabulary in any ordinary sense (yet). RDFS is also special because its specified in the RDF specs, I guess. Pat >I could understand a definition that said 'anybody doing more than >RDF simple entailments isn't doing RDF', but I don't understand >a definition of RDF that includes RDFS but not dublin core, >RSS, DAML+OIL/OWL, etc. > >> (Well, actually, I suppose that an agent could be >> determining whether two RDF graphs RDF entail each other, which is >> different from RDF entailment, but I think that you should be able to get >> my drift.) >> >> peter >-- >Dan Connolly, W3C http://www.w3.org/People/Connolly/ -- --------------------------------------------------------------------- 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 Thursday, 30 May 2002 12:10:11 UTC