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Re: Expressiveness of RDF as Rule Conclusion Language (was Re: W hat is an RDF Query? )

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Fri, 28 Sep 2001 10:39:28 -0400 (EDT)
Message-Id: <200109281439.f8SEdSA27694@pantheon-po04.its.yale.edu>
To: www-rdf-rules@w3.org

   [Gerd Wagner]
   I believe that most people working in the area of logic 
   programming (and deductive database) semantics consider 
   logic programming rules as inference rules and not as
   implications. 

   The intended (i.e. stable) models of a rule [P if not Q]
   are not the same as the intended models of the corresponding
   material implication [not Q -> P] = [P v Q].

This seems like a crucial issue to settle, given the charter of this
group.  I know some people are expecting an RDF-rules system to extend
the logic of RDF in a substantive way.  Such people would want rules
to be interpreted as implications, because then RDF+rules would be
more expressive than RDF alone.

I guess my question is procedural.  Are we allowed or encouraged to
extend RDF in this way?

If not, then it seems like there isn't much to discuss.  As has
already been suggested, a rule would be of the form P -> Q, where P
and Q are both RDF graphs with some nodes variabilized.  They could be
used either forward or backward. 


                                             -- Drew McDermott
Received on Friday, 28 September 2001 10:39:35 GMT

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