11 Computer Chess--A Case Study on the CDC 6600 D. N. L. Levy

In order to be able to view the situation objectively we feel that it would be useful to preface this with a historical review of the development of ideas in this twenty-year-old field. By considering the most important ideas and techniques that are employed in the (currently) best program available, we hope to convince the reader that progress has been very slow despite the multiplicity of programs (and their associated literature) which have appeared since 1950. HISTORICAL REVIEW The most important paper that has appeared on the subject of computer chess is one written by Claude Shannon in 1948 and published two years later (Shannon 1950). Shannon's paper does not describe an actual program, but offers many suggestions for those who are interested in writing one. In this respect Shannon's paper may be compared with one by Jack Good which was also full of sound ideas which could well be included in a successful chess program (Good 1967). Shannon stressed the importance of having a good evaluation function. The features which he considers necessary for inclusion in the evaluation function included material, mobility, five aspects of pawn-structure, four of the positions of pieces, and four of commitments of pieces, attacks and options. He appreciated that such an evaluation function should be used only in the middle-game, and that different principles applied to the opening and endgame phases of chess. He suggested that the values of the coefficients of the function should be determined by'some experimental procedure', and the fact that this statement has never been followed in practice is very surprising.