- From: Jos De_Roo <jos.deroo@agfa.com>
- Date: Thu, 13 Nov 2003 00:53:24 +0100
- To: "pat hayes <phayes" <phayes@ihmc.us>
- Cc: "w3c-rdfcore-wg" <w3c-rdfcore-wg@w3.org>
Pat - this is a milestone! (was surprised to see such a Subject:) It's also the first time as far as I can remember that you don't mention a URI for that version, so it must be special :-) but I'm sure it will show up soon at it's deserved place. The only point I have is that wrt 6. we have not implemented things as Triple(x,y,z) but as y(x,z) which was a choice. Still can't believe it... -- Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/ pat hayes <phayes@ihmc.us> To: w3c-rdfcore-wg@w3.org Sent by: cc: Graham Klyne <gk@ninebynine.org> w3c-rdfcore-wg-req Subject: Final version of semantics uest@w3.org 2003-11-13 12:13 AM Guys, in the interests of full disclosure, here's a summary of the changes made to the semantics document in the last few days. I actually think that this is now *all*. 1. Section subheadings added/changed as per http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Nov/0051.html 2. "name" now includes plain literals, so vocabularies (= sets of names) also may contain plain literals. They are not obliged to, so all old vocabularies are still new vocabularies. 3. 'proper instance' now allows substitution of a plain literal for a bnode. 4. semantic conditions on simple interpretations of a vocabulary V are now restricted to the plain literals in V (as they were formerly for the URIs and typed literals. ) The effect of 2-4 is that all referring expressions (URIrefs and literals) are treated uniformly, and interpretations of a graph are only obliged to interpret the symbols which occur in the graph. All of this is conventional and makes the RDF MT more 'normal'. For justification of why it was needed, see Herman's recent comment on the failure of the RDFS entailment lemma proof http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0150.html (see "To give an example, let A be a URI reference" et seq) No changes to any test cases or entailments arise. 5. minor editorial changes arising from 2-4 above, eg "name or plain literal" -> "name" in several places, and the example in figure 1 now has the literals listed in its vocabulary explicitly. 6. Text added in 1.1 Technical note (Informative): "Readers who are familiar with conventional logical semantics may find it useful to think of RDF as a version of existential binary relational logic in which relations are first-class entities in the universe of quantification. Such a logic can be obtained by encoding the relational atom R(a,b) into a conventional logical syntax, using a notional three-place relation Triple(a,R,b); the basic semantic described here can be reconstructed from this intuition by defining the extension of y as the set {<x,z> : Triple(x,y,z)} and noting that this would be precisely the denotation of R in the conventional Tarskian model theory of the original form R(a,b) of the relational atom. This construction can also be traced in the semantics of the Lbase axiomatic description [LBASE]." This point was raised by at least 3 people at ISWC and in other working groups, so I thought it might be worth drawing attention to. 7. Other minor editorial suggested by Herman, eg "and A(E) is defined" added in the third semantic condition table. None of these change meanings, only clarify or correct errors. 8. The definitions of the Hebrand interpretations in the proof appendix have been simplified somewhat, since they are no longer required to interpret all plain literals. The definition of the 'sur' construction in the RDFS entailment lemma proof has been clarified; several explanatory paragraphs have been added to make the proofs easier to follow, and some typos corrected (which also helps, of course.) Again, for discussion and motivation see Herman's recent email comments. 9. As well as the above, the change log notes the _:x rdf:type rdfs:ContainerMembershipProperty . empty entailment case discussed in earlier emails. Pat -- --------------------------------------------------------------------- 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@ihmc.us http://www.ihmc.us/users/phayes
Received on Wednesday, 12 November 2003 18:53:31 UTC