- From: Brian McBride <bwm@hplb.hpl.hp.com>
- Date: Mon, 29 Apr 2002 08:41:21 +0100
- To: Patrick Stickler <patrick.stickler@nokia.com>, RDF Core <w3c-rdfcore-wg@w3.org>
At 08:45 29/04/2002 +0300, Patrick Stickler wrote: >On 2002-04-28 19:18, "ext Brian McBride" <bwm@hplb.hpl.hp.com> wrote: > > > The know fix > > ============ > > > > In the know fix, we assume that the knowledge that > > > > <jenny> <age> "10" . > > > > really means > > > > <jenny> <age> _:a . > > _:a <xsd:decimal> "10" . > > > > is defined elsewhere > >This is almost but not quite correct. Unless you intended >to specify explicitly somewhere in the graph that > > age rdfd:datatype xsd:decimal . Fair enough, I'm happy to add that as a precondition, though I don't think its really necessary in this case. [...] > > > > The Rule Fix > > ============ > > > > We build a rule mechanism, as in the know fix, into RDF. I think Jos has > > claimed that he has proved something similar, if not the same as this, > > works. No one I have suggested this to has like it, usually for different > > reasons. > > > > <jenny> <ageA> "10" . > > <ageA> <rdfd:datatype> <integer> . > > <ageA> <rdfd:valueProp> <ageB> . > > > > entails: > > > > <jenny> <ageB> _:a . > > _:a <integer> "10". > >There is an alternate way to fix this by rule without introducing >any variant properties. Namely the following closure rule: > > ?s ?p ?l . > ?l rdf:type rdfs:Literal . > ?p rdfd:datatype ?d . > >entails > > ?s ?p ?x . > ?x ?d ?l . > >or > > ?s ?p _:a . > _:a rdfd:lex ?l . I was under the impression this one was subject to some criticism: a) Pat proposed it did not work (supported by Jeremy) http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Apr/0341.html b) it has unfortunate interactions with things like daml:uniqueProperty. What if ?p is unique? The form I suggested is sufficient for the Cannes entailment, which of course is why I resisted your rewriting it. [...] >Why xsi:type? Because that is what xml schema uses. > And why for every occurrence? Every occurrence? >The point of the inline idiom is that the datatyping is implicit >(global, not local). The above is just as local, and more verbose, >than the datatype property idiom: > > <rdf:Description rdf:about="#jenny"> > <age xsd:decimal="10"/> > </rdf:Description> True. But the xsi mechanism may allow us to use DTD's and schemas to override the interpretation of existing RDF. Brian
Received on Monday, 29 April 2002 03:44:04 UTC