Crafty

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Crafty is a chess program written by UAB professor Dr. Robert Hyatt. It is directly derived from Cray Blitz, winner of the 1983 and 1986 World Computer Chess Championships.

On the February 2006 SSDF ratings list, Crafty was 36th with an ELO rating of 2657 [1]. In the World Computer Chess Championships 2004 Crafty won the fourth place with same amounts of points as the third place finisher, Fritz 8, despite running on stronger hardware than all other programs.

Crafty uses the XBoard protocol, and can also be run with the popular free chess interfaces WinBoard or Arena.

Crafty is written in ANSI C with assembly language routines available on some CPUs, and is very portable. The source is available for free.

Crafty pioneered the use of rotated bitboard data structures to represent the chess board. It also includes negascout search, the killer move heuristic, static exchange evaluation, quiescence search, alpha-beta pruning, a transposition table, a refutation table, an evaluation cache, selective extensions, recursive null-move search, and many other features (cf manual). Special editions of the program include enhanced features such as an opening book, positional learning, and an endgame tablebase.

Crafty is one of the programs included in the SPEC-CPU benchmark test. It is also included as an additional engine in Fritz.

The last released version (which includes source) was the 20.x series. 21.6 is the current version but source won't be released until after this year's WCCC tournament.