Los Alamos chess

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6a6 black rookb6 black knightc6 black queend6 black kinge6 black knightf6 black rook6
5a5 black pawnb5 black pawnc5 black pawnd5 black pawne5 black pawnf5 black pawn5
4a4b4c4d4e4f44
3a3b3c3d3e3f33
2a2 white pawnb2 white pawnc2 white pawnd2 white pawne2 white pawnf2 white pawn2
1a1 white rookb1 white knightc1 white queend1 white kinge1 white knightf1 white rook1
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Los Alamos chess setup

Los Alamos chess (or anti-clerical chess[1]) is a chess variant played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. This program was written at Los Alamos Scientific Laboratory by Paul Stein and Mark Wells for the MANIAC I computer[2] in 1956. The reduction of the board size and the number of pieces from standard chess was due to the very limited capacity of computers at the time. The computer still needed about 20 minutes between moves.

The program was very simple, containing only about 600 instructions. It was mostly a minimax tree search and could look four plies ahead. For scoring the board at the end of the four-ply lookahead, it estimates a score for material and a score for mobility, then adds them. Pseudocode for the chess program is described in Figure 11.4 of Newell, 2019.[3] In 1958, a revised version was written for MANIAC II for full 8×8 chess, though its pseudocode was never published. There is a record of a single game by it, circa November 1958 (Table 11.2 of Newell, 2019[3]).

  1. ^ Anderson, Herbert L. (Fall 1986). "Metropolis, Monte Carlo, and the MANIAC" (PDF). Los Alamos Science: 104–105.
  2. ^ Pritchard, D. B. (1994). "Los Alamos Chess". The Encyclopedia of Chess Variants. Games & Puzzles Publications. pp. 175–76. ISBN 0-9524142-0-1.
  3. ^ a b Newell, Allen; Simon, Herbert Alexander (2019). Human problem solving. Brattleboro, Vermont: Echo Point Books & Media. ISBN 978-1-63561-792-4.