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Re: [test] disjunctive entailment without equality

From: Sandro Hawke <sandro@w3.org>
Date: Fri, 12 Dec 2008 12:26:31 -0500
To: Jos de Bruijn <debruijn@inf.unibz.it>
cc: RIF WG <public-rif-wg@w3.org>
Message-ID: <10625.1229102791@ubuhebe>


Talking about
http://www.w3.org/2005/rules/wiki/Disjunctive_Information_from_Negative_Guards_3 
> > who cares about this test case?  Why is it important?
> 
> it shows that you need to reason by cases, which is not usual in
> rule-based systems.

Here's a simpler one, I think:

  Document( 
     Prefix(ex http://example.com/example#) 
     Prefix(pred http://www.w3.org/2007/rif-builtin-predicate#) 
     Group( 
        Forall ?x (ex:q(?x) :- 
                    Or (
                      External(pred:isNotInteger(?x))
                      External(pred:isInteger(?x))
                       )
                   )
      )

entails:
    ex:q(ex:a)

It's logically entailed, but neither a production rule system nor a
prolog-style system is going to figure that out.   (The prolog one
might, by mistake, if it took ex:a as a prolog atom.)

     -- Sandro
Received on Friday, 12 December 2008 17:27:11 GMT

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