- From: Frank Manola <fmanola@mitre.org>
- Date: Tue, 12 Feb 2002 18:12:28 -0500
- To: Brian McBride <bwm@hplb.hpl.hp.com>
- CC: RDF Core <w3c-rdfcore-wg@w3.org>
Brian McBride wrote: > Following up on Frank's excellent reification process, and the decision > we made last week support the provenance use case, I'm wondering if we > can move forward on reification. I wonder if at this weeks telecon we > can decide that the answer to the question: > > Does > > <stmt1> <rdf:type> <rdf:Statement> . > <stmt1> <rdf:subject> <subject> . > <stmt1> <rdf:predicate> <predicate> . > <stmt1> <rdf:object> <object> . > > <stmt2> <rdf:type> <rdf:Statement> . > <stmt2> <rdf:subject> <subject> . > <stmt2> <rdf:predicate> <predicate> . > <stmt2> <rdf:object> <object> . > > <stmt1> <property> <foo> . > > entail: > > <stmt2> <property> <foo> . > > is NO. I hope so too. > > Regarding Graham's entailment: > > <ex:subj> <ex:prop> <ex:obj> . > > entails > > _:r <rdf:type> <rdf:Statement> . > _:r <rdf:subject> <ex:subj> . > _:r <rdf:predicate> <ex:prop> . > _:r <rdf:object> <ex:obj> . > > Whilst I see the sense behind it, I'm a bit concerned by the practical > implications of all the statements in my graph entailing their > reifications. So from a standpoint of simplicity and pragmatics, I > propose that there are NO other entailments in the model theory to do > with reification. Brian-- What do you see the practical implementations of this entailment being? Given the view of <ex:subj> <ex:prop> <ex:obj> as a "stating" (inscription, statement occurrence, aka "triple"), I don't see how we can logically (?) deny that the presense of this triple entails that "there exists a statement with [such and such characteristics]". Haven't we just said it? Does the problem have to do with what we say instances of <rdf:Statement> are (statements or triples)? I.e., we can't say "there exists a statement..." because it isn't one, it's a triple? A more practical issue, it seems to me, is that even if all the statements in your graph entail their reifications, what's the point? There's no way (in RDF) to associate any generated reifications with the original triples. Conversely, if I have some way of identifying triples by associating URIs with them, I can define triples expressing provenance or anything else about them without any special reification syntax. Mind you, given that I can identify individual triples in this way, I still might find it useful to have a "standard" vocabulary, like <rdf:predicate>, for referring to the various parts of the triples, but that wouldn't necessarily have anything to do with provenance. --Frank -- Frank Manola The MITRE Corporation 202 Burlington Road, MS A345 Bedford, MA 01730-1420 mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-875
Received on Tuesday, 12 February 2002 18:07:35 UTC