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Re: RDF semantics: problems with entailment rules rdfs5 and rdfs9

From: pat hayes <phayes@ihmc.us>
Date: Fri, 7 Nov 2003 10:32:15 -0600
Message-Id: <p06001f71bbd172125249@[10.1.31.1]>
To: herman.ter.horst@philips.com
Cc: www-rdf-comments@w3.org

>Two rdfs entailment rules do not seem to be stated
>in sufficient generality.
>This is indicated by the following two counterexamples
>to the rdfs entailment lemma.
>
>Example: graph G consists of triples
>   x subPropertyOf y
>   y subPropertyOf z
>where x y and z are blank nodes.
>In this case the semantics shows that
>G rdfs-entails the triple
>   x subPropertyOf z
>However this triple is not derived by rule rdfs5,
>since this rule requires x y and z to be URIs.
>
>
>A similar problem occurs with rule rdfs9.
>
>Example: graph H consists of triples
>   x subClassOf y
>   z type x
>where z is a blank node.
>According to the semantics, H rdfs-entails the
>triple
>   z type y
>This triple is however not derived by rule rdfs9
>since this rule requires z to be a URI.
>

You are right, of course. These rules should be stated so as to apply 
to blank nodes as well as URIs.  I will make this change.

Pat



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Received on Friday, 7 November 2003 11:32:17 GMT

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