Crafty is a chess program written by UAB professor Dr.

Robert Hyatt Robert Morgan Hyatt (born 1948) is an American computer scientist and programmer. He co-authored the computer chess programs Crafty and Cray Blitz which won two World Computer Chess Championships in the 1980s. Hyatt was a computer science pr ...

, with continual development and assistance from Michael Byrne, Tracy Riegle, and Peter Skinner. It is directly derived from Cray Blitz, winner of the 1983 and 1986 World Computer Chess Championships. Tord Romstad, the author of Stockfish, described Crafty as "arguably the most important and influential chess program ever". Crafty finished in second place in the 2010 Fifth Annual ACCA Americas' Computer Chess Championships. Crafty lost only one game, namely to the first-place winner, Thinker. Crafty also finished in second place in the 2010 World Computer Rapid Chess Championships. Crafty won seven out of nine games, finishing just behind the first-place winner Rybka by only ½ point. In the World Computer Chess Championships 2004, running on slightly faster hardware than all other programs, Crafty took fourth place with the same number of points as the third-place finisher,

Fritz 8 Fritz is a German chess program originally developed for Chessbase by Frans Morsch based on his Quest program, ported to DOS, and then Windows by Mathias Feist. With version 13, Morsch retired, and his engine was first replaced by Gyula Horva ...

. On the November 2007 SSDF ratings list, Crafty was 34th with an estimated Elo rating of 2608. Crafty uses the

Chess Engine Communication Protocol In computer chess, a chess engine is a computer program that analyzes chess or chess variant positions, and generates a move or list of moves that it regards as strongest. A chess engine is usually a back end with a command-line interface with n ...

and can run under the popular chess interfaces

XBoard XBoard is a graphical user interface chessboard for chess engines under the X Window System. It is developed and maintained as free software by the GNU project. WinBoard is a port of XBoard to run natively on Microsoft Windows. Overview Origin ...

and

Winboard XBoard is a graphical user interface chessboard for chess engines under the X Window System. It is developed and maintained as free software by the GNU project. WinBoard is a port of XBoard to run natively on Microsoft Windows. Overview Original ...

. Crafty is written in

ANSI C ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and th ...

with assembly language routines available on some CPUs, and is very portable. The source code is available, but the software is for "personal use" only and redistribution is only allowed under certain conditions. Crafty pioneered the use of rotated

bitboard A bitboard is a specialized bit array data structure commonly used in computer systems that play board games, where each bit corresponds to a game board space or piece. This allows parallel bitwise operations to set or query the game state, or de ...

data structures to represent the chess board, and was one of the first chess programs to support multiple processors. It also includes

negascout Principal variation search (sometimes equated with the practically identical NegaScout) is a negamax algorithm that can be faster than alpha-beta pruning. Like alpha-beta pruning, NegaScout is a directional search algorithm for computing the minima ...

search, the killer move heuristic, static

exchange Exchange may refer to: Physics *Gas exchange is the movement of oxygen and carbon dioxide molecules from a region of higher concentration to a region of lower concentration. Places United States * Exchange, Indiana, an unincorporated community * ...

evaluation,

quiescence search Quiescence search is an algorithm typically used to extend search at unstable nodes in minimax game trees in game-playing computer programs. It is an extension of the evaluation function to defer evaluation until the position is stable enough ...

alpha-beta pruning Alphabeta is an Israeli musical group. Alphabeta or Alpha Beta may also refer to: *The Greek alphabet, from ''Alpha'' (Αα) and ''Beta'' (Ββ), the first two letters *Alpha Beta, a former chain of Californian supermarkets *Alpha and beta anomers ...

, a

transposition table {{no footnotes, date=November 2017 A transposition table is a cache of previously seen positions, and associated evaluations, in a game tree generated by a computer game playing program. If a position recurs via a different sequence of moves, the ...

, a refutation table, an evaluation cache, selective extensions, recursive null-move search, and many other features ( tp://ftp.cis.uab.edu/pub/hyatt/documentation/crafty.man cf manual. Special editions of the program include enhanced features such as an

opening book A chess opening book is a book on chess openings. This is by far the most common type of literature on chess. These books describe many major lines, like the Sicilian Defence, Ruy Lopez, and Queen's Gambit, as well many minor variations of the ma ...

, positional learning, and an

endgame tablebase An endgame tablebase is a computerized database that contains precalculated exhaustive analysis of chess endgame positions. It is typically used by a computer chess engine during play, or by a human or computer that is retrospectively analysin ...

. Crafty was one of the programs included in the SPEC CPU2000 benchmark test. It is also included as an additional engine in

Fritz Fritz originated as a German nickname for Friedrich, or Frederick (''Der Alte Fritz'', and ''Stary Fryc'' were common nicknames for King Frederick II of Prussia and Frederick III, German Emperor) as well as for similar names including Fridolin a ...

Graphical front-ends

GNOME Chess An open-source video game, or simply an open-source game, is a video game whose source code is open-source. They are often freely distributable and sometimes cross-platform compatible. Definition and differentiation Not all open-source games ...

References

{{reflist

External links

Dr. Robert Hyatt's home page

Crafty Download place

Crafty Chess page (Latest Version Downloads)
Chess engines