🚀 go-pugleaf

			      AI SEMINAR
		     UNISYS PAOLI RESEARCH CENTER
				   
		AURORA - An Or-parallel Prolog System

			 Andrzej Ciepelewski
	     Swedish Institute of Computer Science (SICS)


A parallel prolog system has been constructed in a cooperative effort
among Argonne National Lab, University of Manchester and SICS. The
system has been based on a state of the art sequential Prolog. It runs
on multiprocessors with shared memory and is expected to perform
better than on e.g. Sequent Symmetry than the commercial Prolog
systems available today.  The system executes "ordinary" ordinary
Prolog programs withs cuts and side effects keeping the semantics of
sequential execution. Also programs written in Prolog extended with
parallel primitives like "cavalier" commit and unorderd sided-effects
can be excuted.  The system has been designed for portability and
modifiability. It main part, the engine part and the scheduler part
are nicely interfaced. Two quite different schedulers have already
been tried.  Some preliminary performance data has already been
collected, running mostly small search and parsing problems. The
largest program ran so far have been the parallelised SICStus Prolog
compiler and Chat-80. The figures from Sequent Balance 8000 show about
20% parallel overhead in one processor case and close to linear
speed-ups. We are waiting with exitement for figures from Sequent
Symmetry where the system has been recently ported.  In my talk I will
mainly discuss implementation decisions and performance figures.


                      2:00 pm Tuesday, April 26
                           Paoli Auditorium
		     Unisys Paloi Research Center
		      Route 252 and Central Ave.
			    Paoli PA 19311
				   
   -- non-Unisys visitors who are interested in attending should --
   --   send email to finin@prc.unisys.com or call 215-648-7446  --

Tim Finin			finin@prc.unisys.com
Paoli Research Center		..!{psuvax1,sdcrdcf,cbmvax,bpa}!burdvax!finin
Unisys Corporation		215-648-7446 (o)  
PO Box 517, Paoli PA 19301	215-386-1749 (h)