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From: kddlab!icot32.icot.or.jp!hawley@uunet.UU.NET (David John Hawley)
Newsgroups: comp.parallel
Subject: Re: Parallel constraint solving
Keywords: constraints, parallel
Message-ID: <10906@hubcap.clemson.edu>
Date: 11 Oct 90 12:37:22 GMT
Sender: fpst@hubcap.clemson.edu
Organization: Fifth Generation Computing Systems (ICOT), Tokyo, Japan
Lines: 39
Approved: parallel@hubcap.clemson.edu

In article <10852@hubcap.clemson.edu> laffra@serc.nl (Chris Laffra) writes:
>Question:
>
>Does anybody out there has any experience with, or pointers to
>parallel solving of constraint languages problems?

There were some initial results published by the CHIP (constraint
logic programming language) group at ECRC, on combining finite-domain
constraints (i.e. CSP) with the PEPSys parallel logic programming
language/system.  I've heard rumours that this work has been abandoned
because of poor performance.

A visiting researcher did some work on single and all-solutions search
wrt CSP problems, and got quite reasonable results for systems on the order
of 10s of processors. I don't remember the details.

For constraint solving using a symbolic algebra approach (for example,
to solve polynomial equations), there has been some work on
parallelizing the Buchberger algorithm, reported in "Computer Algebra
and Parallelism", Dora & Fitch, Academic Press.  The results are not
encouraging. The CAL group at ICOT is very interested in this
approach, and so we are continuing to explore it's parallization.

>Can you combine constraints with a parallel object-oriented
>language?

There is some work being done at Xerox PARC by Kahn & Saraswat
on this, based on the message-based programming paradigm often used
with concurrent logic languages. However, the class of constraints
considered maybe different from the usual conception.

To the extent that concurrent logic languages can be considered to be
object-oriented, both ourselves and some people at SICS are working
in this area.

---------------------------
David Hawley, ICOT, 4th Lab
csnet: hawley%icot.jp@relay.cs.net uucp:{enea,inria,mit-eddie,ukc}!icot!hawley
ICOT, 1-4-28 Mita, Minato-ku, Tokyo 108 JAPAN. TEL/FAX {81-3-456-}2514/1618