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From: causse@lifia.imag.fr (Olivier Causse)
Newsgroups: comp.ai.shells
Subject: CLIPS problem
Message-ID: <8023@uklirb.informatik.uni-kl.de>
Date: 6 Jun 91 11:01:09 GMT
Sender: shell@uklirb.informatik.uni-kl.de
Reply-To: Olivier Causse <causse@lifia.imag.fr>
Organization: LIFIA - IMAG, Institut National Polytechnique de GRENOBLE, France
Lines: 38
Approved: shell@dfki.uni-kl.de
Posted-Date: Thu Jun  6 11:57:11 GMT 1991


Dear CLIPS users, 
	I fond a very tedious limitation in CLIPS syntax
 (it may not exist in the newest version, tell me if its true).

Here is the problem, I'd like to express the following LHS condition

(defrule problem
  [(<<preceding patterns>>)]
  (not
    (and 
	(A ?x ?y)
	(B ?x ?z&:(neq ?z ?y))
    )
  )
  [(<<other patterns>>)]
=>
 ...
)

I know that AND and OR logic blocks may not be placed inside of a
NOT pattern.

In fact, I'd like to know
	
	1) Why such a restriction ?
	2) How to express the same condition in another (generic) way ?
	3) Do other expert system working with RETE algorithm
	   have the same limit ?

Thanks a lot for any comments.

	Olivier.
-- 
CAUSSE Olivier 	 	A LISP programmer knows the value of everything,
LIFIA - INPG	 	but the cost of nothing.
46, Av. Felix Viallet
38031 Grenoble. CEDEX