- From: Dan Connolly <connolly@w3.org>
- Date: Sat, 20 Oct 2001 09:43:08 -0500
- To: Pat Hayes <phayes@ai.uwf.edu>
- CC: w3c-rdfcore-wg@w3.org, pfps@research.bell-labs.com
[It seems that folks have taken the lack of a reply from me as agreement; not so...] Pat Hayes wrote: > [...] DanC: > >I suggest, again, the following simple abstract syntax: > > > > An RDF graph is a set of triples <S, P, O>; each > > of S, P, O is a term; a term is either an absolute > > URI reference, a bNode, or a literal. > > -- > >http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Oct/0140.html > > > > Well, I'm happy to go along with the more liberal labelling rules, to > be sure. These restrictions only make life more complicated by the > need to avoid exceptional cases in the model theory, closure rules, > etc.. (One of the reasons why I laid out all those conditions on N > and E labels was to make it easy to erase them one at a time :-) > > But this abstract syntax is really just N-triples, It's very close to N-triples... that is: N-triples is designed to closely model this abstract syntax, yes... > and I prefer to > keep the graph as a separate entity. This sort of graph is separate. N-triples syntax is a BNF sort of thing: the statements are ordered; there's whitespace and punctuation, etc. bNodes have a particular syntactic representation, etc. In the graph formalism I'm suggesting, the only thing we specify about bNodes is that they're different from absolute URI references and literals. > >The model theory straightfowardly applies to this liberal > >syntax, I believe. Regarding scope, I think it's straightforward > >to treat bNodes the way local variables are treated in > >traditional logical syntax: you rename them as necessary > >when you merge graphs. > > Yes, it CAN be done that way. I think its uglier, and also it is kind > of cheating, since right now we don't have anything in RDF syntax > (not even in Ntriples) to specify the 'document' boundary. And > remember how much trouble we had with this at the F2F? Yes, we do have something in RDF synatax and in n-triples to specify the document boundary: the document boundary itself. http://www.w3.org/TR/2001/WD-rdf-testcases-20010912/#ntripleDoc http://www.w3.org/TR/2001/WD-rdf-syntax-grammar-20010906/#RDF We don't have a way of putting two scopes into one document, but that's by design (or: by design limitation, as one of our issues suggests). And no, I don't remember how much trouble we had with this at the F2F; I wasn't there the 2nd day. The previous model theory, which was based on n-triples concrete syntax, worked just fine for me. Let me review the record of the 2nd day... It seems to come down to this: Pat: the realization that I have, if I do the MT as attached to the graph, then issues like scope of exist quant go away becauset there are no scopes in the graph. -- http://www.w3.org/2001/sw/RDFCore/20010801-f2f/2001-08-02.html#T16-15-50 If you substitute "set of triples..." as above for graph, the epiphany holds, no? -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Saturday, 20 October 2001 10:43:12 UTC