Los Alamos chess (or anti-clerical chess) is a

chess variant A chess variant is a game related to, derived from, or inspired by chess. Such variants can differ from chess in many different ways. "International" or "Western" chess itself is one of a family of games which have related origins and could be co ...

played on a 6×6 board without

bishops A bishop is an ordained member of the clergy who is entrusted with a position of Episcopal polity, authority and oversight in a religious institution. In Christianity, bishops are normally responsible for the governance and administration of di ...

. This was the first chess-like game played by a computer program. This program was written at

Los Alamos Scientific Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, in ...

by Paul Stein and Mark Wells for the computer in 1956. The reduction of the board size and the number of pieces from standard

chess Chess is a board game for two players. It is an abstract strategy game that involves Perfect information, no hidden information and no elements of game of chance, chance. It is played on a square chessboard, board consisting of 64 squares arran ...

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 Minimax (sometimes Minmax, MM or saddle point) is a decision rule used in artificial intelligence, decision theory, combinatorial game theory, statistics, and philosophy for ''minimizing'' the possible loss function, loss for a Worst-case scenari ...

tree search In computer science, tree traversal (also known as tree search and walking the tree) is a form of graph traversal and refers to the process of visiting (e.g. retrieving, updating, or deleting) each node in a tree data structure, exactly once. S ...

and could look four plies ahead. For scoring the board at the end of the four-ply lookahead, it estimates a score for

material A material is a matter, substance or mixture of substances that constitutes an Physical object, object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical property, physical ...

and a score for

mobility Mobility may refer to: Social sciences and humanities * Economic mobility, ability of individuals or families to improve their economic status * Geographic mobility, the measure of how populations and goods move over time * Mobilities, a conte ...

, then adds them. Pseudocode for the chess program is described in Figure 11.4 of Newell, 2019. In 1958, a revised version was written for

MANIAC II The MANIAC II (''Mathematical Analyzer Numerical Integrator and Automatic Computer Model II'') was a first-generation electronic computer, built in 1957 for use at Los Alamos Scientific Laboratory. MANIAC II was built by the University of Califor ...

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).

Game rules

The starting position is illustrated. All rules are as in

except: * There is no pawn double-step move, nor is there the ''

en passant In chess, ''en passant'' (, "in passing") describes the capture by a Pawn (chess), pawn of an enemy pawn on the same and an adjacent that has just made an initial two-square advance. This is a special case in the rules of chess. The capturi ...

'' capture; * Pawns may not be promoted to bishops; * There is no

castling Castling is a move in chess. It consists of moving the king (chess), king two squares toward a rook (chess), rook on the same and then moving the rook to the square that the king passed over. Castling is permitted only if neither the king ...

Los Alamos trials

The computer played three games. The first was played against itself. The second one was against a strong human player, who played without a queen. The human player won. In the third game, MANIAC I played against a laboratory assistant who had been taught the

rules of chess The rules of chess (also known as the laws of chess) govern the play of the game of chess. Chess is a two-player Abstract strategy game, abstract strategy board game. Each player controls sixteen chess piece, pieces of six types on a chessboar ...

in the preceding week specifically for the game. The computer won, marking the first time that a computer had beaten a human player in a chess-like game.

The second game

White: Martin Kruskal Black:

MANIAC I __NOTOC__ The MANIAC I (Mathematical Analyzer Numerical Integrator and Automatic Computer Model I) was an early computer built under the direction of Nicholas Metropolis at the Los Alamos National Laboratory, Los Alamos Scientific Laboratory. It ...

1. d3 Na4 2. b3 Nb6 3. c3 d4 4. c4 bxc4 5. dxc4 a4 6. Na3 e4 7. Kd2 Ke5 8. f3 e3+ 9. Kc2 axb3+ 10. axb3 Nf4 11. Nd3+ Nxd3 12. Kxd3 Kf4 13. Kc2 Ra5 14. Kb2 Re6 15. Rfd1 Re5 16. Nc2 Rxa1 17. Kxa1 Re6 18. Kb2 Re5 19. Ne1 Qe4 20. fxe4 fxe4 21. Kc2 d3+ 22. exd3 e2 23. Ra1 Re6 24. Ra5 exd3+ 25. Kd2 Re4 26. Rxc5 Re6 27. Nxd3+ Ke4 28. Kxe2 Kd4+ 29. Re5 Rxe5+ 30. Nxe5 Kc5 31. Kd3 Kb4 32. Kd4 Nxc4 33. bxc4 Kb3 34. c5 Kb4 35. c6=Q Kb3 36. Nd3 Ka2 37. Qc3 Kb1 38. Qb2

The third game

White:

Black: Beginner
1.d3 b4 2.Nf3 d4 3.b3 e4 4.Ne1 a4 5.bxa4 Nxa4 6.Kd2 Nc3 7.Nxc3 bxc3+ 8.Kd1 f4 9.a3 Rb6 10.a4 Ra6 11.a5 Kd5 12.Qa3 Qb5 13.Qa2+ Ke5 14.Rb1 Rxa5 15.Rxb5 Rxa2 16.Rb1 Ra5 17.f3 Ra4 18.fxe4 c4 19.Nf3+ Kd6 20.e5+ Kd5 21.exf6=Q Nc5 22.Qxd4+ Kc6 23.Ne5

References

External links

Los Alamos Chess
by Hans L. Bodlaender, ''

The Chess Variant Pages ''The Chess Variant Pages'' is a non-commercial website devoted to chess variants. It was created by Hans Bodlaender in 1995. The site is "run by hobbyists for hobbyists" and is "the most wide-ranging and authoritative web site on chess variants". ...

''
Los Alamos Vierschach
b
Jörg Knappen
''The Chess Variant Pages''
A short history of computer chess
by Frederic Friedel
BrainKing.com
- internet server to play Los Alamos chess. {{Early history of video games Chess variants Computer chess 1956 in chess Board games introduced in 1956