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Re: TEST: 6 of 7: empty universe example,

From: Jos De_Roo <jos.deroo@agfa.com>
Date: Thu, 24 Jul 2003 01:07:25 +0200
To: pfps@research.bell-labs.com
Cc: jjc@hpl.hp.com, www-webont-wg@w3.org, www-webont-wg-request@w3.org
Message-ID: <OF0EA546F7.14919215-ONC1256D6C.007D6FC2-C1256D6C.007F0505@agfa.be>


Peter F. Patel-Schneider wrote:
> From: Jeremy Carroll <jjc@hpl.hp.com>
> Subject: TEST: 6 of 7: empty universe example,
> Date: Wed, 23 Jul 2003 19:20:15 +0300
>
> >
> > Peter?
> > (for book-keeping)
> >
> > I had some outstanding actions on this one.
> >
> > At one point it seemed that I would need to make owl:Thing finite but
> > non-empty to get different behaviour in DL and Full; it now appears
that
> > owl:Thing can be empty in DL, os I have reduced the test to
> >
> > owl:Thing owl:equivalentClass owl:Nothing
> >
> >
http://www.w3.org/2002/03owlt/editors-draft/draft/proposedByFunction#Thing-001

> >
http://www.w3.org/2002/03owlt/editors-draft/draft/proposedByFunction#Thing-002

> >
> > this test is slightly different from the one that I was actioned to
produce.
> >
> > Jeremy
>
> Hmm.  There may have been a slight glitch here at some time.
>
> Right now, neither the direct semantics nor the rdfs semantics require
that
> the OWL DL universe of discourse is non-empty.
>
> As Pat pointed out empty universes can cause problems in languages with
> quantification.  I don't think that these problems surface in OWL.


I really can't make any sense of following being consistent

[[
<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:owl="http://www.w3.org/2002/07/owl#"
    xml:base="http://www.w3.org/2002/03owlt/Thing/consistent001" >

  <owl:Class rdf:about="http://www.w3.org/2002/07/owl#Thing">
    <owl:equivalentClass rdf:resource
       ="http://www.w3.org/2002/07/owl#Nothing"/>
  </owl:Class>

</rdf:RDF>
]]

which is basically and globally the content of
http://www.w3.org/2002/03owlt/Thing/consistent001
(but it's currently forbidden to access it
and maybe it better stay's like that ;-))


> peter
--
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Wednesday, 23 July 2003 19:24:12 GMT

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