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Re: Layering bug

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 03 Jul 2003 11:39:27 +0100
Message-ID: <3F0407DF.2060409@hplb.hpl.hp.com>
To: Mehrdad Omidvari <Mehrdad.Omidvari@networkinference.com>
CC: pat hayes <phayes@ihmc.us>, www-webont-wg@w3.org



Mehrdad Omidvari wrote:


> However, the "Model Theory" of OWL DL (like the MT of FOL) insists that
> the universe is non-empty.


Ahhh I had missed that, I will need to rework the counterexamples.

Indeed the direct semantics says that
EC(owl:Thing) = R
and
R is non-empty

so

owl:Thing owl:equivalentClass owl:Nothing .

is false.

The new problems will have to assert that owl:Thing is a singleton set, and 
then do some magic with there only being one class and one property.

This may suggest a different fix of changing the assertion that "R is 
non-empty" to "R is infinite".

Jeremy
Received on Thursday, 3 July 2003 06:43:59 GMT

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