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Re: Searching simple opensource chess program

From: -nospam-
Subject: Re: Searching simple opensource chess program
Date: Sun, 19 Dec 2004 19:22:32 GMT
User-agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.3) Gecko/20040910

Paul Pichota wrote:

For a university project I want to compare different algorithms (minimax, alpha-beta and some variants). So I am looking for rather simple and working opensource program where I can easily exchange the algorithms.

I have tried the same stuff but I came to following conclusion: In order to evaluate an algorithm you have to cross-check the results with the results obtained from a brute-force search. The brute-force attack must come to a position where the score is agreed with all parties involved.

This has 3 major drawbacks.

1) Brute force search in chess is very time consuming. Move generation is complex and takes a lot of time if a large tree is to be searched. (e.g. if you try the go game, you will understand where the compexity lies.) 2) A definite chess score is obtained in the same chess program in the evaluation function. When comparing the chess score obtained with other chess programs or a human evaluation, scores may vary. Only mate and technical draw positions are definite. 3) Before all rules (ep, 50moves, 3 fold-repetition) are implemented, it takes a lot of time and effort. Effort that does not contribute to the algorithm development.

So in order to compare different algorithms, I designed a program with different algorithms and different games. The only thing you have to do is to select the algorithm, and the game-ruleset. Because of the complexity of a chess program, it is left out however. But I did include checkers, connect 4, tictactoe, draughts, othello/reversi... etc. I also implemented different algorithms and you can ask for a move to be generated with all algorithms in parallel. You can easily compare the output from minimax/brute-force/alpha-beta/negascout. It is called strategicgames.

> I have already tried GNU Chess but the search routine is rather
> complex because of various prunings, heuristics etc.

I can send you the source of my chess program named 'Belofte'. I can assure you, it is much simpler than gnuchess. You can test playing against it on Finger belofte for more details. Mail me for getting the source code.

You can also download the source code of the strategic games. It can be downloaded from

PS: Strategic Games does have some errors in the negascout and the move-generation for some checkers variants.... Feel free to correct.

Good luck,


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