Bits and pieces: constructing chess endgame databases on parallel and vector architectures

Abstract

An endgame database for chess encodes optimal lines of play for a specific endgame involving a small number of pieces. The computation of such a database is feasible for as many as six pieces provided the inherent parallelism in the problem is fully exploited. Two computer architectures which can do this are the SIMD CM-2 and the vector multiprocessor YMP. For each machine the computer programs operate on sets of chess positions, each position represented by a single bit. The high-level algorithm is an iterative backtracking procedure. After describing endgame databases and classifying the complexity of endgames we outline the algorithms and give some details of their implementation in Fortran for parallel and vector architectures. For endgames with five or more pieces it is important to use the symmetries of the chess board to reduce storage requirements, and we indicate briefly how this can be done for the vector architecture. Some timing comparisons are presented.