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Re: RIF and QL

From: Francois Bry <bry@ifi.lmu.de>
Date: Fri, 27 Jan 2006 11:26:10 +0100
Message-ID: <43D9F542.5090406@ifi.lmu.de>
To: Enrico Franconi <franconi@inf.unibz.it>, W3C RIF WG <public-rif-wg@w3.org>

Enrico Franconi wrote:

>However, there may be several kinds of these 'connections': most of  
>them are based on a model-theoretic characterisation rather than on  
>entailment 
>
Entailment is defined in logic in model theoretic terms: F |= G (formula
F entails formula G) iff all models of F are models of G. Refering to
this model theoretic definition, proof methds for entilment are defined.

>Let us restrict attention to the RDF and OWL ontology/knowledge- 
>representation languages (we have at least to consider those two, as  
>per our charter). In order to super-simplify our life, let us in  
>addition restrict our attention to the case when those queries are  
>atomic: atomic binary predicates (a triple for RDF, a role for OWL)  
>and atomic unary predicates (a class in OWL).
>
>By adopting the 'trivial' semantics above, it is impossible to  
>correctly capture correctly, for example, the function-free horn  
>clause fragment of SWRL (which is, if you think a little about it, a  
>special case of the above but with FOL semantics); 
>
I do not understand why. Enrico, could you plewase give a clue to
saimple-minded readers like me?

Regards,
-- 

Francois
Received on Friday, 27 January 2006 10:26:14 GMT

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