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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 11:18:19 -0600
Message-Id: <p06001f72bbd1825822c5@[]>
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
>   z type y
>This triple is however not derived by rule rdfs9
>since this rule requires z to be a URI.
>Herman ter Horst

Further to the above, I have amplified the textual explanation of the 
conventions, and gone through section 7 to bring the conventions in 
line in all the rule tables, so that the use of uuu, xxx, etc. is 
uniform throughout and corresponds exactly and unambiguously to the 
minimal syntactic needed to state the rules.

This was the original intention, but details got buried in multiple edits.

BTW this has the amusing consequence that 'www' is now used as a 
schematic for any subject, which has a kind of poetic justice to it.

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Received on Friday, 7 November 2003 12:19:43 UTC

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