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Re: On production rules and phase I&II

From: Hassan At-Kaci <hak@ilog.com>
Date: Wed, 08 Mar 2006 14:58:40 +0100
Message-ID: <440EE310.5080904@ilog.com>
To: Francois Bry <bry@ifi.lmu.de>
CC: "Peter F. Patel-Schneider" <pfps@inf.unibz.it>, public-rif-wg@w3.org

Francois Bry wrote:

> 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?

You did.

> Francois

-hak


-- 
Hassan At-Kaci
ILOG, Inc. - Product Division R&D
tel/fax: +1 (604) 930-5603 - email: hak @ ilog . com
Received on Wednesday, 8 March 2006 13:58:11 GMT

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