SAL

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SAL, (Search and Learn) a general game playing and learning open source program for any two-player board game of perfect information, written by Michael Gherrity as subject of his Ph.D. thesis A Game Learning Machine. SAL is written in C|ANSI C.

=Description= The rule of the game is defined by subroutines for generating legal moves, as already provided for Tic-tac-toe, Connect Four, and Chess in the source files ttt.c, connect4.c, and chess.c. One of them, or an appropriate implementation of another game, needs to be copied to game.c for building SAL to play that game.

Search
For all games, SAL performs a two-ply, full-width alpha-beta search plus consistency search, which is a generalized quiescence search as proposed by Don Beal.

Evaluation
The game independent evaluation is implemented as neural network for each side. The inputs to the network are features representing the board, the number of pieces of each type on the board, the type of piece just moved, the type of piece just captured (if any), and several features considering pieces and squares under attack. The neural network evaluator is trained by temporal difference learning to estimate the outcome of the game, given the current position.

=Results=
 * In Tic-tac-toe, SAL learned to play perfectly after 20,000 games
 * In Connect four, SAL learned to defeat an opponent program about 80% of the time after 100,000 games
 * In Chess, after 4200 games against GNU Chess, SAL evolved from a random mover to a reasonable, but still weak chess player

=See also=
 * Chess Engines with Neural Networks
 * General Game Playing
 * HAL
 * Learning Chess Programs
 * Metagamer
 * Zillions of Games

=Publications=
 * Michael Gherrity (1993). A Game Learning Machine. Ph.D. thesis, University of California, San Diego, advisor Paul Kube, pdf, pdf
 * Marco Block, Maro Bader, Ernesto Tapia, Marte Ramírez, Ketill Gunnarsson, Erik Cuevas, Daniel Zaldivar, Raúl Rojas (2008). Using Reinforcement Learning in Chess Engines. Concibe Science 2008, Research in Computing Science: Special Issue in Electronics and Biomedical Engineering, Computer Science and Informatics, Vol. 35, pdf

=Forum Posts=
 * Subject: Re: Game Learning by Mike Gherrity, ai-repository, July 1, 1994
 * Sal or neurochess by ethan ara, CCC, September 06, 2011

=External Links=

Game Player

 * SAL from Machine Learning in Games by Jay Scott
 * SAL source code

Misc

 * Sal (disambiguation) from Wikipedia
 * SAL 9000 fictional computer in 2010: Odyssey Two

=References= Up one level