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

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 23 Jul 2003 13:53:33 -0400 (EDT)
Message-Id: <20030723.135333.38029159.pfps@research.bell-labs.com>
To: jjc@hpl.hp.com
Cc: www-webont-wg@w3.org

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.

Received on Wednesday, 23 July 2003 13:53:43 UTC

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