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Re: iff

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 18 Apr 2003 16:38:38 -0500
Message-Id: <p05111b00bac61cbf3251@[10.0.100.12]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: w3c-rdfcore-wg@w3.org

>Hmm.  Under this reasoning
>
>ex:foo rdf:type owl:Restriction .
>ex:foo owl:onProperty rdf:type .
>ex:foo owl:hasValue rdfs:Class .
>
>implies
>
>ex:foo rdfs:subClassOf rdfs:Class.
>
>I don't think so.

I do.  The argument: suppose  (x type foo);  then  (x type Class) 
because of the restriction on type; but x is arbitrary, so  (foo 
subClassOf Class) by the iff condition on rdfs:subClassOf.

And this seems to me to make intuitive sense, since the restriction 
amounts to saying that anything that foo is true of must be of type 
rdfs:Class, so foo is a subclass of rdfs:Class. Obviously it would 
work for any class, not just rdfs:Class. Also in OWL-Full it would 
work with ranges as well, since they also have iff semantics.

Pat

PS the logical translation of the above amounts to
foo(x) implies type(x,Class)
which with the axiom
type(x,y) iff x(y)
gives
foo(x) implies Class(x)
with x free, ie universally quantified; which is a sufficient condition for
Subclass(foo, Class)
because
Subclass(x,y) iff (all (z)(x(z) implies y(z) )




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Received on Friday, 18 April 2003 17:38:41 EDT

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