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RE: Layering bug

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 3 Jul 2003 17:44:05 +0200
To: "pat hayes" <phayes@ihmc.us>, "Mehrdad Omidvari" <Mehrdad.Omidvari@networkinference.com>
Cc: <www-webont-wg@w3.org>

> >I don't see this as a problem for OWL DL.
> >OWL DL (like FOL) does allow you to *assert* that the universe is empty
> >(for example by saying that "owl:thing equivalentClass owl:Nothing". In
> >FOL you would say forAll x (x != x)).
> >There is no harm in this, apart from making your ontology or theory
> >inconsistent.
> As I understand the current exchange, the claim is that this
> assertion is *consistent* in OWL-DL; hence my message.
> Pat

Yes Pat that was the point, but Mehrdad is right to say that it is not
correct. OWL-DL explicitly excludes the possibility that owl:Thing is empty,
which surprises me. But still, making owl:Thing a singleton still permits
demonstration of the bug.

Received on Thursday, 3 July 2003 11:43:57 UTC

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