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Re: need to determine what RDF is

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 30 May 2002 13:22:05 -0400
To: bwm@hplb.hpl.hp.com
Cc: danbri@w3.org, www-rdf-comments@w3.org, em@w3.org, w3c-semweb-cg@w3.org
Message-Id: <20020530132205E.pfps@research.bell-labs.com>

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 13:24:11 GMT

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