- From: pat hayes <phayes@ai.uwf.edu>
- Date: Mon, 5 May 2003 15:57:26 -0500
- To: fmanola@mitre.org
- Cc: w3c-rdfcore-wg@w3.org
>Yes; as noted in an earlier interaction with Brian, this also applies >to RDFS. As I said, the Primer would have to cover this point in some >way (given that at the point where the Primer talks about Collections, >it hasn't gotten to Schema yet). Right. I felt a similar pressure, which is why there is a text comment in the RDF section saying that RDFS will add some more constraints to the RDF vocabulary. The relationship between RDF and RDFS entailment is kind of sneaky, in fact. I put into the 'pure' RDF semantics all those conditions that could be stated 'directly' in terms of triples using just the pure RDF namespace. But this 'directly' is a delicate distinction, since one could state this condition without actually mentioning rdfs:domain, eg by imposing a semantic condition connecting rdf:first, rdf:type and rdf:List, without mentioning anything in the RDFS namespace at all if <x,y> in IEXT(I(rdf:first)) then <x, I(rdf:List)> in IEXT(I(rdf:type)). and similarly, by the way: if <x,y> in IEXT(I(rdf:next)) then <x, I(rdf:List)> in IEXT(I(rdf:type)). if <x,y> in IEXT(I(rdf:next)) then <y, I(rdf:List)> in IEXT(I(rdf:type)). if <x,y> in IEXT(I(rdf:subject)) then <x, I(rdf:Statement)> in IEXT(I(rdf:type)). if <x,y> in IEXT(I(rdf:predicate)) then <x, I(rdf:Statement)> in IEXT(I(rdf:type)). if <x,y> in IEXT(I(rdf:object)) then <x, I(rdf:Statement)> in IEXT(I(rdf:type)). Its just that this is all so much easier to say directly once the rdfs:domain/range is introduced, that it seemed kind of silly to write it into RDF, even though one could reasonably claim that these are all RDF rather than RDFS conditions, since they apply to the RDF vocabulary and can be stated as restrictions on it. However, there isn't any reason why you need to be so fussy in the Primer, seems to me (??): you could just talk about things being in domains and ranges before formally introducing rdf:domain and rdfs:range. This would then allow you to introduce the idea when talking about RDF, then refer back to it to 'explain' what rdfs:domain and rdfs:range mean. Or, if folk prefer, I could add these conditions to the RDF semantics, stated in the above style as semantic conditions, and supply appropriate RDF closure rules (which would of course be redundant in RDFS, but that's OK) Any votes for this? It occurs to me that it might also help de-fuse some of the howls about reification and collections having 'no semantics'. It would be quick to do at this stage, so don't feel that it would be a great slow-up or anything; and I could claim it as editorial since it really is only a matter of presentation, and nobody outside this WG is going to give a damn about the finer points of the RDF/RDFS distinction, I would guess. If I hear two yeses and no noes, I'll put it into a revised draft :-) Pat > >--Frank > >Graham Klyne wrote: >> >> At 09:20 30/04/2003 -0400, Frank Manola wrote: >> >Or rather, whether this is true *in RDF* (as opposed to in OWL). The >> >point is that, as I read the Semantics document, the only semantic >> >condition imposed on the collection vocabulary is that the type of rdf:nil >> >must be rdf:List. This, of course, doesn't apply to the subject of an >> >rdf:first, so the inference Tim wants drawn would seem to be a semantic >> >extension which might be true for OWL, but not necessarily for RDF per >> >se. It seems to me the explanation would have to cover this >>point in some way. >> >> In the semantics doc, there's also: >> >> [[ >> rdf:first rdfs:domain rdf:List . >> rdf:rest rdfs:domain rdf:List . >> ]] >> -- http://www.w3.org/2001/sw/RDFCore/TR/WD-rdf-mt-20030117/#rdfs_interp >> >> from which the rest flows through RDFS entailments. >> >> #g >> >> ------------------- >> Graham Klyne >> <GK@NineByNine.org> >> PGP: 0FAA 69FF C083 000B A2E9 A131 01B9 1C7A DBCA CB5E > >-- >Frank Manola The MITRE Corporation >202 Burlington Road, MS A345 Bedford, MA 01730-1420 >mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-8752 -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes s.pam@ai.uwf.edu for spam
Received on Monday, 5 May 2003 16:57:28 UTC