Chess and Computers. David Levy

Transcription

1 Chess and Computers David Levy

2 First published 1976 Copyright David Levy 1976 Printed in the United States of America All rights reserved. No part of this work may be reproduced, transmitted, or stored in any form or by any means, without the prior written consent of the Publisher. Computer Science Press, Inc Fall River Lane Potomac, Maryland ISBN Paper

3 Table of Contents 1 Chess Machines How Computers Play Chess The Early History of Computer Chess The Modern Era of Computer Chess Computer Chess Tournaments Current Research and Future Prospects Stop Press Bibliography

4 Preface For some time now, I have felt that the time is right to write a book about Computer Chess. Ever since the first attempts at chess programming were made, some twenty five years ago, interest in the subject ha"s grown from year to year. During the late 1950s the subject was first brought to the attention of the public by an article in Scient(fic American, and less than a decade later a chess program was competing in a tournament with humans. More recently, there have been tournaments in which the only participants were computer programs. and when the first World Computer Championship was held in Stockholm in 1974 the event was an outstanding success. Laymen often doubt the value of investing in a subject so esoteric as computer chess, but there is definitely considerable benefit to be gained from a study of the automisation of chess and other intellectual games. If it proves possible to play such games well by computer, then the techniques employed to analyse and assess future positions in these games will also be useful in other problems in long-range planning. I have tried to make this book both interesting and instructive. Those who understand anything at all about chess but who have no knowledge of computers, will be able to follow my description of how computers play chess. Those with a knowledge of both areas will still find much to interest them. I have included several examples of computer play. These are intended to be entertaining, as well as illustrative of the way that programs play. I have taken particular pains to include a thorough coverage of Soviet programming efforts because these efforts have, until now, been largely ignored by the literature in the West. I should like to thank John Littlewood who translated Vigneron's article Les automats from the original French, Katya Young who translated most of the material that was originally published in Russian, and my wife, Jacqueline, who helped to read the proofs. I should also like to thank David Bronstein, Mikhail Donskoy and David Slate for their help, and Ben Mittman and Monty Newborn for their efforts in promoting computer chess. Lastly, I must thank Dennis Gilles, without whom this book would probablv not have been written. David Levy London, October 1975

5 Introduction 'Chess is the Art of Human Reason '. Augustus. Duke of Brunswick Chess is a fascinating game. Over the centuries it has come to be regarded as the intellectual game par excellence. so complex is its nature and so varied are the positions that can arise even within a very few moves. Yet chess is simple enough to be learned within a few minutes and it is a game that can be enjoyed at all levels of play from beginner to grandmaster. It has become such a popular game in the 20th Century that the number of registered players in the Soviet Union can be measured in millions. and it has been so profusely written about that there are more books available on chess than those devoted to all other sports and pastimes put together. But chess is still only a game. What then would be the value to society if someone managed to create a machine that could play perfect. or at least grandmaster level chess? This question has often been asked and before describing how man has tried to program computers to play chess I shall endeavour to explain why he thinks it is a worthwhile task. Chess is a game of planning. To play the game well it is necessary to be able to create in one's mind a plan that conforms to the necessities and potentialities of a given position. It is true that in many positions the correct move can be found by pure calculation but it is not these positions that really distinguish the master from the amateur. A two move combination will be found by the club player nearly as often as by a master. but the correct long-term plan will be discovered much more frequently by the master than by the club player. If we could write a computer program that could play good chess we could (presumably) use similar programming techniques to solve other problems in longrange planning. Is it any more difficult to win the World Chess Championship than it is to plan the year's budget for a nation or to solve a difficult diplomatic crisis with the flair of a Kissinger? I doubt it. Probably it is easier. I have always found it most difficult to convince non-scientists of the value of computer chess. But then fifty years ago I expect that I would have had at least as much difficulty convincing society of the value of building a machine that could smoke cigarettes. From the fact that smoking machines have since been built and that as a direct result of the research performed with these machines startling advances have

6 been achieved in medical knowledge, I think that any non-scientist must agree that 'What use will it have?' is not a verv good argument to be employed against an esoteric looking research project. A frequently heard argument of a different type, is 'If man succeeds in building a machine that can win the World Chess Championship, what fun will there be left in the game?' In reply I would say 'Boats have been sailing the seas for centuries but I still like to swim'. In this book I explain, in rather simple terms, how computers play chess. I trace the history of computer chess in order to show how much (or little) advance has been made during the past thirty years. I describe the 'thought processes' of chess programs and discuss their limitations and their achievements. I discuss some of the stronger chess programs that have been written in recent years and I show how some of the problems of computer chess have been solved while on others there has been little or no progress. I have written this book in such a way that it can be understood by any chess player (i.e. anyone who knows the moves and the rules of the game) even though he might never even have heard of an electronic computer, let alone know how one works. If you are interested in science but cannot play chess then your complaint is easily and painlessly remedied. I hope that my readers will find the subject of computer chess interesting and some of my examples of computer play entertaining.