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Re: comments on current (6 Nov) draft of RDF MT document

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 08 Nov 2002 12:16:39 -0500 (EST)
Message-Id: <20021108.121639.56467860.pfps@research.bell-labs.com>
To: jeen.broekstra@aidministrator.nl
Cc: phayes@ai.uwf.edu, www-rdf-interest@w3.org

From: Jeen Broekstra <jeen.broekstra@aidministrator.nl>
Subject: Re: comments on current (6 Nov) draft of RDF MT document
Date: Fri, 08 Nov 2002 15:07:14 +0100

> Peter F. Patel-Schneider wrote:
> 
> [snip]
> 
> (Caveat: I can not find the Nov 6 WD that you are referring to, but
>   assume that it is not such a dramatic change from the April 29 version
>   that the following no longer holds).
> 
>  > 7/ The RDFS closure rules are incomplete, even if the above problems
>  > are fixed.  Therefore, the RDFS entailment lemma is false.
>  >
>  > For example, 
>  >	rdf:type rdfs:domain foo . 
>  >	a b c . 
>  > RDFS-entails
>  > 	a rdf:type foo . 
>  > because every resource has rdfs:Resource as a type, as
>  > I have pointed out before.
> 
> Isn't this example covered by subsequent application of rdfs4a and rdfs2?
> 
> a b c -> a rdf:type rdfs:Resource (rdfs4a)
> 
> a rdf:type rdfs:Resource
> 	& a rdfs:domain foo -> a rdf:type foo (rdfs2)

Yes.  My fault again for not following through on all the rules, and
instead going with my instincts.

>  > Also, 
>  > 	a b c . 
>  > RDFS-entails 
>  > 	a rdf:type rdfs:Class . 
>  > because every resource is a subClassOf rdfs:Resource and, 
>  >	rdfs:subClassOf rdfs:domain foo . 
>  >	a b c . 
>  > RDFS-entails 
>  >	a rdf:type foo . 
>  > because every resource is a subClassOf rdfs:Resource
> 
> I'm baffled by these two observations. Where is it specified that every
> resource is a subClassOf rdfs:Resource?

The new definition of rdfs:subClassOf is iff.  The class extension of every
resource is a subset of the class extension of rdfs:Resource.  Therefore
every resource is an rdfs:subClassOf rdfs:Resourse.

> Best regards,
> 
> Jeen

peter
Received on Friday, 8 November 2002 12:16:51 GMT

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