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Re: Question on OWL tests

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 19 May 2004 10:12:05 -0400 (EDT)
Message-Id: <20040519.101205.15640671.pfps@research.bell-labs.com>
To: guido.naudts@just.fgov.be
Cc: public-webont-comments@w3.org

From: "Naudts, Guido" <guido.naudts@just.fgov.be>
Subject: Re: Question on OWL tests
Date: Wed, 19 May 2004 13:36:52 +0200

> I've done some research on the internet, without any results. Could
> anybody tell me what exactly are the OWL comprehension rules? And why do
> they impede the introduction of a concept in the conclusions? 
> (If I missed something important in the standard documents, please
> accept my apology).
> Thanks, Guido

I quick search in OWL S&AS
http://www.w3.org/TR/owl-semantics/semantics-all.html
for ``comprehension'' provides a table of the Comprehension conditions
(principles) in OWL.


They are needed, for example, so that 

	ex:a rdf:type ex:b .
	ex:a rdf:type ex:c .

OWL-entails

	ex:a rdf:type _:d .
	_:d owl:intersectionOf _:l1 .
	_:l1 rdf:first ex:b .
	_:l1 rdf:rest _:l2 .
	_:l2 rdf:first ex:c .
	_:l2 rdf:rest rdf:nil .

Without the first comprehension principle this entailment would not hold
because 

	ex:a rdf:type ex:b .
	ex:a rdf:type ex:c .

would not OWL-entail

	_:l1 rdf:first ex:b .
	_:l1 rdf:rest _:l2 .
	_:l2 rdf:first ex:c .
	_:l2 rdf:rest rdf:nil .

i.e., there would not need to be a list containing ex:a and ex:b so there
would be no way to form its intersection.

Yes, this is all an artifact of having to encode OWL syntax in
semantically-meaningful RDF triples.

Peter F. Patel-Schneider
Bell Labs Research
Received on Wednesday, 19 May 2004 10:11:31 GMT

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