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Re: bug in RDF model theory having to do with rdfs:subClassOf and rdfs:subPropertyOf

From: pat hayes <phayes@ai.uwf.edu>
Date: Sun, 22 Sep 2002 18:23:40 -0500
Message-Id: <p05111b25b9b3e7ab4475@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org

>I was wrong in my initial speculation that making the semantic constraint for
>rdfs:subClassOf an iff constraint would not have RDFS-observable
>If the semantic constraint for rdfs:subClassOf is changed to an iff
>constraint then
>	rdf:type rdfs:domain foo .
>would entail
>	rdfs:Resource rdfs:subClassOf foo.

Ah, most ingenious. OK, but I think this is harmless. It doesn't work 
for arbitrary domains, and the domain of rdf:type is already required 
to be the universe. What you have noticed is that trying to restrict 
that domain to a subset of the universe only makes the universe 
smaller, in effect. The moral is that one cannot sensibly use RDF to 
restrict the domain of the rdf:type property. Which is in fact hardly 
surprising, since to do so would be to change the definition of 
'class' and hence of subClassOf.

Also it depends on exactly how the condition is worded. I'll think 
about that some more.


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Received on Sunday, 22 September 2002 19:23:36 UTC

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