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Re: RDF and OWL compatibility

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Mon, 9 Jan 2006 14:31:19 +0100
Message-Id: <F54EDBB0-0DC6-4DA7-99DB-91B0EFDEE5C4@inf.unibz.it>
Cc: Jos de Bruijn <jos.debruijn@deri.org>, public-rif-wg@w3.org
To: Dave Reynolds <der@hplb.hpl.hp.com>

On 5 Jan 2006, at 15:51, Dave Reynolds wrote:
> On the question of bNodes in the head, I hear the argument that it  
> is not sufficient to just treat these as new Skolem constants but  
> my intuitive understanding of the issue is too weak. It would be  
> really helpful if someone could construct a test case which  
> demonstrates the difference in results that arise between correct  
> treatment of bNodes in the head versus treatment as Skolem  
> constants. In the concrete cases I've seen where bNodes are used in  
> the head of rules they seem to be intended as a form of anonymous  
> gensym - so the Skolem constant semantics may be the more  
> practically useful interpretation.

A a naive gensym would fail the use case  <http://www.w3.org/2005/ 
rules/wg/wiki/Managing_incomplete_information>, where two examples  
(in section "9.4. (Rules involving generation of unknown)") show how  
you can make things wrong with a naive use of skolem constants to  
implement the existential variables in the head.

cheers
--e.
Received on Monday, 9 January 2006 13:31:34 GMT

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