PROLOG-REQUEST@SU-SCORE.ARPA (Chuck Restivo, The Moderator) (09/14/86)
PROLOG Digest Monday, 15 Sep 1986 Volume 4 : Issue 50
Today's Topics:
Announcement - Parallel Inference System
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Date: Thu, 11 Sep 86 17:08:33 EDT
From: Jack Minker <minker@mimsy.umd.edu>
Subject: Parallel Inference System at Maryland
AI and Database Research Laboratory
at the
University of Maryland
Jack Minker - Director
The AI and Database Research Laboratory at the Univer-
sity of Maryland is pleased to announce that a parallel
logic programming system (PRISM) is now operational on the
McMOB multiprocessosor. The system uses up to sixteen pro-
cessors to exploit medium grained parallelism in logic pro-
grams. The underlying ideas behind PRISM appeared in [Eis-
inger et. al., 1982] and [Kasif et. al., 1983].
The McMOB multiprocessor is a direct offspring of ZMOB
[Reiger et. al.,1980]. It consists of sixteen Motorola
MC68010 processors interconnected via a high speed belt.
PRISM consists of several parts: a user host interface
that exists on the host machine; a set of machines (moblets)
designated as problem solvers (PSMs); a set of machines
designated as Extensional Database Machines (EDB) that store
ground atomic formulae (relational database tables); and, a
set of machines designated as Intensional Database Machines
(IDB) that store procedures (the general rules in the sys-
tem). The system can also optionally include Constraint
Machines (CM) that use user-supplied constraints to prune
unsatisfiable paths in the proof tree.
The system supports both AND and OR parallelism. The
user can specify control in terms of the sequence of atoms
to be executed in a set of problems to be solved. Atoms can
be executed in parallel, sequentially, or as specified by a
partial ordering. Similarly procedures can be specified as
being executed sequentially, in parallel, or as specified by
a partial order. The PSM has been written in a modular
fashion to permit alternative control structure programs to
be incorporated in the system. Alternative node and literal
selection algorithms may be incorporated as part of the con-
trol structure. The user may specify the configuration
(i.e., the number of moblets required as a minimum) in which
a problem is to be run. If additional moblets are avail-
able, the PRISM will automatically take advantage of them.
A large number of problems are currently being pro-
grammed in PRISM and experiments will be run with these to
determine the effectiveness of PRISM as a problem solving
system.
The major research directions in the laboratory over
the coming year will be devoted to the following areas:
(1) Experimentation Using PRISM
(2) Control Structure Investigations
(3) Expert systems and PRISM
(4) Parallel problem solving and Architecture Issues
If you would like further information on PRISM, please
contact MINKER@MARYLAND or MADHUR@MARYLAND. We would also
be very interested in hearing from people who may have prob-
lems we could run on PRISM.
References:
1. Eisinger, N., Kasif, S., and Minker, J., "Logic Pro-
gramming: A Parallel Approach", in Proceedings of the
First International Logic Programming Conference, Mar-
seilles, France, 1982.
2. Kasif, S., Kohli, M., and Minker, J., "PRISM - A Paral-
lel Inference System for Problem Solving", in IJCAI-83,
Karlsruhe, Germany, 1983.
3. Rieger, C., Bane, j., and Trigg, R., "ZMOB: A Highly
Parallel Multiprocessor", University of Maryland, TR-
911, May 1980
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End of PROLOG Digest
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