Thank you both for responding.
I can see that Ernest's solution leverages filtering, but I don't have a
clue what's going on with the CCP stuff.
I suspect I'd be better off focussing on the proper use of Jess first.
A bit off topic, but I get a "variable not bound" exception if I use a
variable in the pattern to replace the hard-coded '50' and '100' values. Is
it illegal to reference a bound variable in a pattern? (offending code
snippet below...)
-Mitch
(defrule find-solution
(coin (denomination penny) (count ?cp) (amount ?ap))
(coin (denomination nickel)
(count ?cn&:(<= (+ ?cp ?cn) ?coinCounts)) <<-- Generates an error
(amount ?an&:(<= (+ ?ap ?an) ?totalAmt)))
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of [EMAIL PROTECTED]
Sent: Monday, August 11, 2003 1:20 PM
To: [EMAIL PROTECTED]
Subject: Re: JESS: Newbie question (Coin puzzle-SOLVED)
I think Win Carus wrote:
> Ernest's approach reduces matching time substantially and does make it
> possible in a realistic time to compute the $2.00 change combinations
> using a version of your script modified as he suggest.
>
> However ... the "generate-and-test" approach is still very
> memory-intensive and a still-better alternative would be to use the CCP
> approach implemented by Futtersack and Labat
> (http://www.droit.univ-paris5.fr/futtersack/english/research/CCP/).
> Although the approach discussed refers only to a CLIPS implementation,
> Jess code is also available for download. The basic idea behind CCP is
> to assert facts only as needed; and backtrack only to sensible
> alternative search paths. This can reduce memory use substantially and
> make some problems possible to solve (or possible to solve in reasonable
> times).
>
Thanks, Win, for bringing this up again. Professor Futtersack used to
be a frequent correspondent in Jess's early days. Mr. Carus has
suggested to me recently that a form of CCP might gainfully be
integrated into Jess; this is on my teetering stack of worthwhile
things to investigate. I think this would be a Really Good Thing.
---------------------------------------------------------
Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://herzberg.ca.sandia.gov
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