Chess engine

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A chess engine is a computer program that can play the game of chess.

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[edit] Interface

Traditionally, the term chess engine referred to a chess playing program that did not have its own user interface. Typically they ran on user interfaces such as XBoard on Linux or WinBoard on Windows. Nowadays, many commercial engines, historically sold tightly integrated with their own interface, now allow additional engines to be loaded. Popular examples include the Chessmaster and Chessbase family of engines.

[edit] Protocols

The command line interface of GNU Chess became the initial de facto standard, first supported by XBoard. There is now a newer protocol, the Universal Chess Interface.[1].

Many engines support both protocols. Both protocols have their supporters, although Universal Chess Interface has an edge on usability for end-users.

[edit] Increasing strength

Chess engines increase in playing strength each year. This is partly due to the increase in processing power that enables calculations to be made to ever greater depths in a given time. In addition, programming techniques have improved enabling the engines to be more selective in the lines that they analyse and to acquire a better positional understanding.

Some chess engines use endgame tablebases to increase their playing strength during the endgame. An endgame tablebase is a database of all possible endgame positions with small groups of material. Each position is conclusively determined as a win, loss, or draw for the player whose turn it is to move, and the number of moves to the end with best play by both sides. Endgame tablebases in all cases identify the absolute best move in all positions included (identifying the move that wins fastest against perfect defense, or the move that loses slowest against optimal opposition). Such tablebases are available for all 3-6 man positions (counting the kings) and some 7-man combinations. When the manoevering in an ending to achieve an irreversible improvement takes more moves than the horizon of calculation of a chess engine, an engine is not guaranteed to find the best move without the use of an endgame tablebase, and in many cases can fall foul of the 50 move rule etc. as a result. Some experts have pointed out the potential for faulty use of endgame tablebases by programmers, leading to worse play.

[edit] Comparison between engines

[edit] World Computer Chess Championship

From the results of the World Computer Chess Championship a current view of the relative strengths of chess engines can be deduced. The 2006 championship was won by the Deep Junior program. The top four programs were commercial engines but Spike, a freely available engine, finished joint 5th. [2]

[edit] Chess engine rating lists

[edit] Engine categories

[edit] Freely available chess engines

[edit] Pedagogical engines

These open source chess programs were expressly written to teach the craft of chess programming.

[edit] Commercial programs

These chess programs are sold commercially. Most of these also include their own user interface.

[edit] Personal programs

These programs are personal or research projects which may have competed in tournaments or online, but are otherwise unavailable to the public.

[edit] Dedicated hardware

These chess playing systems include custom hardware or run on supercomputers.

[edit] Historical programs

These chess programs run on obsolete hardware.

[edit] See also

[edit] External links

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