Editing GNU Chess

{{Short description|Free software chess engine}}
{{Use dmy dates|date=March 2023}}
{{Infobox software
 | name = GNU Chess
 | logo = Heckert GNU white.svg
 | screenshot = [[Image:XBoard GNUChess.png|250px|GNU Chess 6.0.0 on XBoard 4.5.1]]
 | caption = GNU Chess 6.0.0 running with the [[XBoard]] front end, v. 4.1.5.
 | developer = [[GNU Project]]
 | released = {{Start date and age|1984}}
 | latest release version = {{wikidata|property|preferred|references|edit|Q494713|P348|P548=Q2804309}}
 | latest release date = {{wikidata|qualifier|preferred|single|Q494713|P348|P548=Q2804309|P577}}
 | latest preview version = {{wikidata|property|preferred|references|edit|Q494713|P348|P548=Q51930650}}
 | latest preview date = {{wikidata|qualifier|preferred|single|Q494713|P348|P548=Q51930650|P577}}
 | operating system = [[Linux]], [[Unix]], [[macOS]], [[Microsoft Windows|Windows]]
 | genre = [[Computer chess]]
 | license = 2010{{efn|GPL-3.0-or-later since 2010-01-03, version 5.08.}}: [[GNU General Public License|GPL-3.0-or-later]]<br />1992{{efn|GPL-2.0-or-later since 1992-05-30, version 4.0.43.}}: [[GNU General Public License|GPL-2.0-or-later]]<br />1986: Chess-GPL{{efn|GNU Chess General Public License}}<ref>{{cite web|url=https://opensource.apple.com/source/Chess/Chess-49/gnuchess.subproj/COPYING|title=GNU Chess General Public License|date=1986}}</ref><ref>{{cite newsgroup|url=https://groups.google.com/g/ont.general/c/DA4P3edfSAI|title=yetti's Christmas/New Year goodies (gnu chess)|last=Yigit|first=Ozan|date=1986-12-17|newsgroup=ont.general}}</ref>
 | website = {{URL|www.gnu.org/software/chess/}}
}}
{{Chess programming series}}
'''GNU Chess''' is a [[free software]] [[chess engine]] and [[command-line interface]] [[chessboard]]. The goal of [[GNU]] Chess is to serve as a basis for research, and as such it has been used in numerous contexts.

GNU Chess is free software, licensed under the terms of the [[GNU General Public License#Version 3|GNU General Public License version 3]] or any later version, and is maintained by collaborating developers. As one of the earliest [[computer chess]] programs with full [[source code]] available, it is one of the oldest for [[Unix]]-based systems and has since been [[Porting|ported]] to many other [[Computing platform|platforms]].

== Features ==
GNU Chess 6.2.5 is rated at 2661 [[Elo rating system|Elo points]] on [[CCRL#Computer chess rating lists|CCRL]]'s 40-moves-in-2-minutes list.<ref>{{cite web|url=http://ccrl.chessdom.com/ccrl/404/cgi/engine_details.cgi?match_length=30&eng=GNU%20Chess%206.25%2064-bit|archive-url=https://web.archive.org/web/20230207062903/http://ccrl.chessdom.com/ccrl/404/cgi/engine_details.cgi?match_length=30&eng=GNU%20Chess%206.25%2064-bit|title=CCRL Blitz - GNU Chess 6.25 64-bit|archive-date=February 7, 2023}}</ref> For comparison, the [[Comparison of top chess players throughout history|strongest human player]], [[Magnus Carlsen]], has achieved an Elo rating of 2882. On the same list, [[Fritz (chess)|Fritz 8]] was rated at 2665 Elo,<ref>{{Cite web |url=http://ccrl.chessdom.com/ccrl/404/rating_list_all.html |title=CCRL Blitz - February 5, 2023 |access-date=6 April 2023 |archive-date=7 February 2023 |archive-url=https://web.archive.org/web/20230207062909/http://ccrl.chessdom.com/ccrl/404/rating_list_all.html |url-status=dead }}</ref> and that program in the 2004 [[Human–computer_chess_matches#2004|Man vs Machine World Team Championship]] beat grandmasters [[Sergey Karjakin]], [[Veselin Topalov]] and reached a draw with [[Ruslan Ponomariov]].

It is often used in conjunction with a [[Graphical user interface|GUI]] program such as [[XBoard]] or [[GNOME Chess]], where it is included as the default engine. Initial versions of XBoard's [[Chess Engine Communication Protocol]] were based on GNU Chess's [[command-line interface]]. Version 6 also supports the [[Universal Chess Interface]] (UCI). Since version 6.1 GNU chess supports a graphical mode for terminal emulators.
[[File:Gnuchess-terminal.png|thumb|GNU chess terminal graphic mode]]

== History ==
The first version of GNU Chess was written by Stuart Cracraft. Having started in 1984 in collaboration with [[Richard Stallman]] prior to his founding of the [[GNU Project]], GNU Chess became one of the first parts of GNU.{{Citation needed |date=June 2019}}

GNU Chess has been enhanced and expanded since. Versions from 2 to 4 were written by John Stanback. Version 5 of GNU Chess was based on the Cobalt chess engine written by Chua Kong-Sian.<ref>{{Cite web |last=Cracraft |first=Stuart |date=October 10, 1999 |title=GNU Chess 5 |url=https://groups.google.com/g/gnu.chess/c/UGpLeswpTSU/m/5UtPTsLqhB8J |website=[[Google Groups]]}}</ref>

In 2011, GNU Chess transitioned to version 6, which is based on Fabien Letouzey's [[Fruit (software)|Fruit 2.1 chess engine]].  According to [[Chess Engines Grand Tournament|CEGT]]<ref>{{cite web|url=http://www.husvankempen.de/nunn/40_40%20Rating%20List/40_40%20All%20Versions/rangliste.html|archive-url=https://web.archive.org/web/20110308175817/http://www.husvankempen.de/nunn/40_40%20Rating%20List/40_40%20All%20Versions/rangliste.html|archive-date=2011-03-08|title=The CEGT rating list}}</ref> version 5.60 of this code base is stronger than Fruit 2.3, the latest version of that chess engine.

== See also ==
{{Portal|Free and open-source software|Video games}}
* [[List of open-source video games]]
*[[GNU Go]]
*[[XBoard]]

==Notes==
{{notelist}}

==References==
{{Reflist|30em}}

==External links==
* {{official website|https://www.gnu.org/software/chess/}}

{{GNU}}

{{DEFAULTSORT:Gnu Chess}}
[[Category:1984 software]]
[[Category:Chess engines]]
[[Category:DOS games]]
[[Category:Free chess software]]
[[Category:Free educational software]]
[[Category:GNU Project software|Chess]]
[[Category:GP2X games]]
[[Category:Linux games]]
[[Category:Unix games]]
[[Category:Video games developed in the United States]]
[[Category:Windows games]]