W3C home > Mailing lists > Public > www-webont-wg@w3.org > March 2002

Re: more on a same-syntax extension from RDF(S) to OWL

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 04 Mar 2002 09:29:04 -0500
To: jos.deroo.jd@belgium.agfa.com
Cc: www-webont-wg@w3.org
Message-Id: <20020304092904D.pfps@research.bell-labs.com>
From: "Jos De_Roo" <jos.deroo.jd@belgium.agfa.com>
Subject: Re: more on a same-syntax extension from RDF(S) to OWL
Date: Mon, 4 Mar 2002 01:07:21 +0100

> 
> [...]
> 
> > But the whole point is that, using your terminology,
> >
> >
> > log:entails
> >    c' owl:oneOf ( r' ) .
> >    r' a owl:Restriction .
> >    r' owl:onProperty rdf:type .
> >    r' hasClassQ c' .
> >    r' maxCardinalityQ "0" .
> >
> > so an empty hypothesis entails a contradiction, which is a paradox.
> 
> well, I wonder how an empty hypothesis could entail the graph
> 
>   _:c owl:oneOf ( _:r ) .
>   _:r a owl:Restriction .
>   _:r owl:onProperty rdf:type .
>   _:r owl:hasClassQ _:c .
>   _:r owl:maxCardinalityQ "0" .
> 
> we have tried hard to achieve such a result with
> our understanding of owl-theory, but we can only
> achieve that after having asserted e.g.
> 
>   <pp#d> owl:oneOf ( <pp#s> ) .
>   <pp#s> a owl:Restriction .
>   <pp#s> owl:onProperty rdf:type .
>   <pp#s> owl:hasClassQ <pp#d> .
>   <pp#s> owl:maxCardinalityQ "0" .
> 
> and that contains indeed a contradiction
> 
> --
> Jos De Roo

The message that I sent out concerned how and why this sort of inference
follows from a few basic entailments.  The basic intuition is that to get
the sort of entailments that are required, such as

	john a A .
	john a B .
entails
	john a _:1 .
	_:1 owl:intersectionOf ( A B ) .

you end up with a lot of things that are in every interpretation, including
something like
	
   _:1 owl:oneOf ( _:2 ) .
   _:2 a owl:Restriction .
   _:2 owl:onProperty rdf:type .
   _:2 hasClassQ _:1 .
   _:2 maxCardinalityQ "0" .


So, to be more precise it should have been


log:entails
   _:1 owl:oneOf ( _:2 ) .
   _:2 a owl:Restriction .
   _:2 owl:onProperty rdf:type .
   _:2 hasClassQ _:1 .
   _:2 maxCardinalityQ "0" .


peter
Received on Monday, 4 March 2002 09:29:46 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:57:48 GMT