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Re: The Cannes Entailment [was: Coming to grips with the entailment put forth by Jeremy]

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 29 Apr 2002 08:41:21 +0100
Message-Id: <5.1.0.14.0.20020429082714.0311b6b0@0-mail-1.hpl.hp.com>
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 EDT

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