- From: Dan Connolly <connolly@w3.org>
- Date: Thu, 06 Dec 2001 17:26:09 -0600
- To: Pat Hayes <phayes@ai.uwf.edu>, w3c-rdfcore-wg@w3.org
A couple clarifications... Dan Connolly wrote: > > Pat Hayes wrote: > > > [...] > > >I understand the P/P++ proposal to actually muck > > >with that level of interpretation; they actually > > >allow model-theoretic interpretaions where the objects of > > > <rdfs:label>10</rdfs:label> > > >and > > > <ex:shoeSize>10</ex:shoeSize> > > >denote different things. > > > > > >The S/DC/PL proposals don't muck with things at that level. > > > > I'm not sure to what intuitions you are appealing when you use the > > term 'muck with'. > > I'm appealing to all the complications where, in order to > figure out what the 10 in <rdfs:label>10</rdfs:label> denotes, > you might have to get/trust other files, do inference, > etc. to find a range for rdfs:label. > > I'm appealing to the fact that simple RDF documents don't > even entail themselves. ... don't even ential themselves in the P-style proposal. > > Leaving aside the rhetoric, it is true that the > > P-style proposals allow different occurrences of the same lexical > > literal to denote different values. But isn't that exactly what XML > > datatyping does, > > No. XML datatyping has no notion of propositional content, > model theory, entailment, or any of that sort of stuff. > > And it certainly doesn't have the requirement that is > so central to RDF: that the meaning of an RDF document, > as a logical formula, is self-evident. To put it > in black-and-white, testable terms: that every > RDF document entails itself. > > The XML Schema design accepts all the wishy-washiness where > if you start with document X, depending on > whether you choose to pair it with schema S1 or S2, the ...>10<... > might denote an integer or a string. ... might be associated with the type integer or string. The XML Schema spec doesn't speak of denotation. > > and aren't we under a mandated requirement to > > respect that? > > No; we have mandate to make the datatypes in XML Schemas > (date, integer, float, ...) available in the RDF world. > > We don't have to mess up RDF's self-evident-ness to do it, > as proposals S/P/DC show. > > > More generally, isn't that what ANY datatyping scheme > > does? > > No, as perl and BCPL programmers know... and logicians, evidently... > > > If all literals were unambiguous then there would be no need to > > even use datatyping schemes. Traditional logical notations for > > example have felt no need for datatyping schemes for exactly this > > reason: they fix the meanings of things like numerals, and use other > > syntactic constructions to denote things like character strings. > > Bingo! Then we'll be in good company. > > > If a > > literal always denotes the same value, then there really is no > > datatyping in the language at all, seems to me. I'm not averse to > > that idea; it makes for a cleaner model theory , for one thing. > > Amen. > > > But > > I would like us to call a spade a spade, and if we decide to go with > > one of the S/DC/PL proposals, to say loud and clear that we have > > simply eliminated data-typing from RDF and do not plan to support XML > > datatypes. > > Datatyping was never in RDF, to my mind. > But we certainly plan to support XML datatypes, in the same > way that the logic folks support character strings > built out of integers. > > -- > Dan Connolly, W3C http://www.w3.org/People/Connolly/ -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 6 December 2001 18:26:11 UTC