Crafty is a
chess program written by
UAB professor
Robert Hyatt, with development and assistance from Michael Byrne, Tracy Riegle, and Peter Skinner. It is derived from
Cray Blitz Cray Blitz was a computer chess program written by Robert Hyatt, Harry L. Nelson, and Albert Gower to run on the Cray supercomputer. It was derived from "Blitz" a program that Hyatt started to work on as an undergraduate. "Blitz" played its first ...
, winner of the 1983 and 1986
World Computer Chess Championships. Tord Romstad, co-author of
Stockfish
Stockfish is unsalted fish, especially cod, dried by cold air and wind on wooden racks (which are called "hjell" in Norway) on the foreshore. The drying of food is the world's oldest known preservation method, and dried fish has a storage li ...
, 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, 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 behind the first-place winner Rybka by 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. On the November 2007
SSDF ratings list, Crafty was 34th with an estimated
Elo rating
The Elo rating system is a method for calculating the relative skill levels of players in zero-sum games such as chess or esports. It is named after its creator Arpad Elo, a Hungarian-American chess master and physics professor.
The Elo system wa ...
of 2608.
Crafty uses the
Chess Engine Communication Protocol and can run under the 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
Original ...
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 the ...
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 d ...
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 mi ...
search, the
killer move heuristic, static
exchange
Exchange or exchanged may refer to:
Arts, entertainment and media Film and television
* Exchange (film), or ''Deep Trap'', 2015 South Korean psychological thriller
* Exchanged (film), 2019 Peruvian fantasy comedy
* Exchange (TV program), 2021 Sou ...
evaluation,
quiescence search,
alpha-beta pruning Alphabeta or Alpha Beta may also refer to:
* Alphabeta, an Israeli musical group
* Alpha Beta, a former chain of Californian supermarkets
* The Greek alphabet, from ''Alpha'' (Αα) and ''Beta'' (Ββ), the first two letters
* Alpha and beta anome ...
, 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. Special editions of the program include enhanced features such as an
opening book, positional learning, and an
endgame tablebase
In chess, the endgame tablebase, or simply the tablebase, is a computerised database containing precalculated evaluations of chess endgame, endgame positions. Tablebases are used to analyse finished games, as well as by chess engines to evaluate ...
.
Crafty was one of the programs included in the
SPEC CPU2000 benchmark test.
It is also included as an additional engine in
Fritz
Fritz is a common German language, German male name. The name originated as a German diminutive of Friedrich (given name), Friedrich or Frederick (given name), Frederick (''Der Alte Fritz'', and ''Stary Fryc'' were common nicknames for King Fred ...
.
Graphical front-ends
*
GNOME Chess
References
{{reflist
External links
Robert Hyatt's home page
Chess engines