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Re: On production rules and phase I&II

From: Francois Bry <bry@ifi.lmu.de>
Date: Wed, 08 Mar 2006 14:56:29 +0100
Message-ID: <440EE28D.8050502@ifi.lmu.de>
To: "Peter F. Patel-Schneider" <pfps@inf.unibz.it>
CC: public-rif-wg@w3.org

Peter F. Patel-Schneider wrote:
> I don't understand which universe I've fallen into here.
>
> In my universe, production rule systems derived from OPS5.  
>
> In my universe, OPS5 allowed rules like
> 	(p (parent ^parent <x> ^child <y>)
> 	   (ancestor ^ancestor <y> ^descendant <z>)
> 	   -->
> 	   (make ancestor ^ancestor <x> ^descendant <z>))
>
> In my universe, this was a recursive rule.
>
> What is different in this universe?
>   
My understanding is that Hassan - riogthly - pointed out that using a
production rule like the above (and its evaluator), one can implements a
recurrsive deduction rule stating that parents of ancestors are
themselves ancestors.

Thus, the situation is like implementing the evaluation of a recursive
deduction rule using a while-block in an imperative programme: this
programme is not recursive even though it uimplements something which is
recursive.

Hassan, did I got your point?

Francois
Received on Wednesday, 8 March 2006 13:56:36 GMT

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