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Re: Some basic questions about OWL-Full

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 23 Oct 2007 10:15:24 -0400 (EDT)
Message-Id: <20071023.101524.238930507.pfps@research.bell-labs.com>
To: phayes@ihmc.us
Cc: jjc@hpl.hp.com, public-owl-dev@w3.org

From: Pat Hayes <phayes@ihmc.us>
Subject: Re: Some basic questions about OWL-Full
Date: Tue, 23 Oct 2007 08:58:28 -0500

> 
> >Peter F. Patel-Schneider wrote:
> >>
> >>For homework:  Is EquivalentProperties(owl:sameAs owl:differentFrom)
> >>  	 	       itself inconsisten?
> >>
> >
> >I'm afraid I'm several years' late on my (easier) homework of:
> >    Is (*empty*) itself inconsistent?
> 
> Yes, in RDF (and conventional FOL). This is the 
> only assumption of Tarskian semantic theory, that 
> there is something in the universe. One can build 
> a 'free' logic which allows an empty universe, 
> but then its proof theory can't have the usual 
> rules of instantiation and generalization, which 
> allow the inferences
> 
> (forall (x) (foo x))  |==   (foo A) for some 
> 'new' name A |==  (exists (x)(foo x))
> 
> Pat

I think Jeremy meant an empty KB, i.e., whether OWL Full is trivial or
not.

peter
Received on Tuesday, 23 October 2007 14:25:39 GMT

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