Distributed Game Tree Search on a Massively Parallel System

During the World Computer Chess Championships in Madrid, November 1992, our distributed chess program ZUGZWANG ran on a 1024 processor machine and nished second place without having lost a game. This article presents measurements that show the behaviour of ZUGZWANG using massive parallelism. We will show that the network used to interconnect the processors is a crucial point for the eeciency of our algorithm. This will be done by comparing the behaviour of our program with 256 processors using a DeBruijn network, a torus and a grid as interconnection network. On the other side we will point out, that even grid structured networks suuce to produce reasonable eeciency with up to 1024 processors.