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Re: another revision of semantics document

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 22 Aug 2002 10:04:18 -0400
To: phayes@ai.uwf.edu
Cc: www-webont-wg@w3.org
Message-Id: <20020822100418Q.pfps@research.bell-labs.com>

[Note:  I will be using Pat's abbreviations for lists and restrictions
throughout.  I have also included owl:Thing and owl
] 

Pat's claim just before Section 2.3 is incorrect.

The claim is that OWL entailment, as defined in my semantics document
  http://www-db.research.bell-labs.com/user/pfps/owl/semantics.html
is the same as entailment over OWL structure interpretations (which I will
call OWL/RDF structure entailment.

This is not correct, for several reasons.

First, 
	Class(C)
OWL entails
	SubClassOf(sub=C super=unionOf(C C))
but
	C rdf:type owl:Class .
does not OWL structure entail
	C rdfs:subClassOf _:u .
	_:u owl:unionOf [C C] .
because of the definition of rdfs:subClassOf in the RDFS model theory.


Second,

	ObjectProperty(foo Symmetric)
	SubClassOf(sub=owl:Thing super=restriction(foo value=a))
	Individual(a type=A)
	Individual(b type=B)
	DifferentIndividuals(a b)
	DisjointClasses(A B)
	Class(C complete restriction(oof minCardinality(3)))

does not OWL entail

	Individual(a type=C)

but the translation into RDF does produce an OWL/RDF structural entailment,
because there are three different classes (A, B, and rdfs:Resource) in the
domain of discourse and each of them is related to a via foo.


peter
Received on Thursday, 22 August 2002 10:04:28 GMT

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