Side-effects in PloSys OR-parallel Prolog on
distributed memory machines

Project CNRS-INRIA APACHE
LMC-IMAG, B.P. 53, F-38-41
Grenoble Cedex 9, Franceee
{Eric.Morel,Jaques.Briat,Jacques.Chassin,Claudio.Geyer}@imag.fr

Abstract
The aim of the logic programming system PloSys is to offer most Prolog functionalities on distributed memory parallel computers as well as networks of personal computers. The PloSys computational model exploits OR-parallelism. It is designed to implement cut and side-effects while keeping low the number of messages exchanged between processors. It is a multi-sequential model based on copying. Scheduling is centralised as is the management of cut and side-effects. The scheduler keeps up to date the knowledge of the left-most worker in the scope of each cut. A PloSys prototype was implemented and its first results, on IBM SP-1, are promising.