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Re: need to determine what RDF is

From: Brian McBride <bwm@HPLB.HPL.HP.COM>
Date: Thu, 30 May 2002 18:53:38 +0100
Message-Id: <5.1.0.14.0.20020530183335.075a0460@15.144.25.13>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: danbri@w3.org, www-rdf-comments@w3.org, em@w3.org, w3c-semweb-cg@w3.org

Thank you Peter.

Follows a point of clarificiation and a more extreme test case.

By Universal Entailment I meant to  include entailments sanctioned by any 
specification that should apply.  I think Peter is taking it to mean 
entailments sanctioned by the RDF specifications.  These are equivalent if 
the RDF specifications sanction the 'importing' of semantics defined 
elsewhere.  The terms 'open semantics' and 'closed semantics' come to mind, 
but they probably have a different technical meaning defined elsewhere.

Test case 3:

Given:

   <rdfs:Class rdf:about="http://example.org/foo">
     <rdfs:comment>this class can be used interchangably with 
http://example.org/bar</rdfs:comment>
   </rdfs:Class>
   <rdf:Description rdf:about="http://example.org/foobar">
     <rdf:type rdf:resource="http://example.org/foo">
   </rdf:Description>

Is an expert witness entitled to stand up in court and state that a 
system*, given the above input, behaved correctly according to the RDF 
specifications, when it concluded:

   <rdf:Description rdf:about="http://example.org/foobar">
     <rdf:type rdf:resource="http://example.org/bar>
   </rdf:Description>

Brian

* to duck issues of machine understanding of natural language, I consider 
that I am a system.



At 13:22 30/05/2002 -0400, Peter F. Patel-Schneider wrote:
>From: Brian McBride <bwm@hplb.hpl.hp.com>
>Subject: Re: need to determine what RDF is
>Date: Thu, 30 May 2002 17:34:33 +0100
>
> > At 11:09 30/05/2002 -0400, Peter F. Patel-Schneider wrote:
> >
> > >The ``deep'' issue is that there continues to be claims that RDF
> > >encompasses information not encoded in RDF graphs (or in RDF-defined
> > >documents that can be transformed into RDF graphs).   The wording
> > >associated with rdfs:comment appears to be capable of supporting this 
> view,
> > >although, as Pat Hayes has pointed out, it really does not.  I suppose 
> that
> > >this could be considered to be just wordsmithing, but wordsmithing taking
> > >into account the implicit view of RDF.
> >
> > One of the techniques we have found particularly useful in RDFCore has 
> been
> > reducing issues to one or more test cases.  Do you think it might be
> > possible to create a test case for this issue.
> >
> > I'm maybe beginning to get a glimmer of what the problem is, but I'm not
> > sure.  Ramblings that are certainly technically incompetent but illustrate
> > an idea follow.  I think I'm struggling to make more precise a phrase of
> > Peter's "is not part of RDF".
> >
> > Postulate the existence of Universal Entailment (since "RDF entailment"
> > already means something else).  The Universal Entailment of an RDF 
> graph is
> > the graph which includes all the triples that a processor is entitled to
> > conclude from the original graph.
> >
> > I think Peter's position is that Universal Entailment contains only 
> triples
> > entailed by RDF(S) entailment.
> >
> > Brian
>
>
>Here are two:
>
>Case 1:
>
>Does:
>
><ex:John> <ex:loves> <ex:Mary> .
>
><_:s1> <rdf:type> <rdf:Statement> .
><_:s1> <rdf:subject> <var:?x> .
><_:s1> <rdf:predicate> <ex:loves> .
><_:s1> <rdf:object> <var:?y> .
>
><_:s2> <rdf:type> <rdf:Statement> .
><_:s2> <rdf:subject> <var:?y> .
><_:s2> <rdf:predicate> <ex:loves> .
><_:s2> <rdf:object> <var:?x> .
>
><_:s1> <log:implies> <_:s2> .
>
>Universally-Entail
>
><ex:Mary> <ex:loves> <ex:John> .
>
>
>Case 2:
>
>Does:
>
>   <ex:best-friend> <rdf:type> <daml:UniqueProperty> .
>   <ex:age> <rdf:type> <daml:UniqueProperty> .
>   <ex:bob> <ex:best-friend> <ex:margaret> .
>   <ex:bob> <ex:best-friend> <ex:peggy> .
>   <ex:peggy> <ex:age> "35" .
>   <ex:margaret> <ex:best-friend> <ex:susan> .
>   <ex:margaret> <ex:best-friend> <ex:jane> .
>   <ex:susan> <ex:age> "43" .
>   <ex:jane> <ex:age> "55" .
>   <daml:UniqueProperty> <rdfs:label> "UniqueProperty" .
>   <daml:UniqueProperty> <rdfs:comment> "compare with maxCardinality=1, 
> e.g., ..." .
>   <daml:UniqueProperty> <rdfs:subClassOf> <rdf:Property> .
>
>Universally-Entail
>
>   <ex:margaret> <ex:age> "35" .
>
>My answer is NO, for both.
>
>peter
Received on Thursday, 30 May 2002 13:55:05 GMT

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