- From: Sandro Hawke <sandro@w3.org>
- Date: Sun, 19 Dec 2004 21:20:10 -0500
- To: tammet@staff.ttu.ee
- Cc: www-rdf-logic@w3.org, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
"Peter F. Patel-Schneider" <pfps@research.bell-labs.com> writes: > My understanding of the problem was to write extra semantic conditions on > RDF(S) interpretations, and thus generate an embedding/encoding of binary > first-order logic into a semantic extension of RDF(S). You can't extend > the syntax at the same time, however, which means that you have to encode > formulae as triples somehow, and these triples retain their RDF(S) meaning. > > However, it doesn't seem to me that Sandro has the same understanding. No, that's exactly what I want, too. I would also like the whole exercise to be, in the end, simple enough that the community interested in rule languages and RDF can be comfortably with the results. I keep hearing about projects using RDF encodings of Horn or FOL, and they turn out to have either unclear or inconsistent semantics. If we're going to move to a standard here, it would help to clear up whether it is possible to do this kind of encoding properly. I can't imagine, for instance, that the approach taken by SWRL 0.6 would ever be approved in a W3C Recommendation, for the reasons I outlined in the team comment [1]. If Peter can convince me that it's not possible to write the desired semantic condition, I can help him convince others that a different path needs to be taken for rule languages. If I can convince Peter it *is* possible (and we figure out how onerous it is), then a standard can use it (or not, but because the difficulty has been actually weighed). Unfortunately, I can't just hand Peter the desired semantic conditions. I don't really know how to write them in the formalism of RDF Semantics [2]. My understanding is that Peter doesn't either and suspects it's not possible to write them. Meanwhile, it is "obvious" how to write them informally and with subtle errors. Something like "put the FOL expressions in a string literal and assert it", as I explored in my previous e-mail [3]. So I've been trying to write them using a formalism in which I have a good sense of how to do it and with which I think I can detect most if not all subtle errors. It may also show the way in which to do it in the desired formalism. I'll try to return to the substance of this thread shortly. Peter's raised to questions I need to explore. -- sandro [1] http://www.w3.org/Submission/2004/03/Comment (in the "RDF" section) [2] http://www.w3.org/TR/rdf-mt/ [3] http://lists.w3.org/Archives/Public/www-rdf-logic/2004Dec/0022.html
Received on Monday, 20 December 2004 02:17:16 UTC