Documentation forGNU Chessis available online, asis documentation for most GNU software. You mayalso find more information aboutGNU Chessby runninginfo chessorman chess,or by looking at/usr/share/doc/chess/,/usr/local/doc/chess/,or similar directories on your system. A brief summary is available byrunning gnuchess --help.
Gnu Chess Source Code
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GNU Chess is free software, licensed under the terms of the 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 ported to many other platforms.
It is often used in conjunction with a 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.
In 2011, GNU Chess transitioned to version 6, which is based on Fabien Letouzey's Fruit 2.1 chess engine. According to CEGT[7] version 5.60 of this code base is stronger than Fruit 2.3, the latest version of that chess engine.
GNU Chess,the open source chess engine of the Free Software Foundation. GNU Chess was initially written by Stuart Cracraft in the mid 80s, joined by John Stanback who contributed his own code to GNU Chess 2 and 3 which was laboriously and meticulously well-written [2]. Dozens of developers have enhanced GNU Chess over the times. Version 5 was a complete rewrite by Chua Kong Sian, incorporating his chess program Cobalt and Cracraft's Gazebo [3]. Fabien Letouzey is the primary author of GNU Chess 6, based on Fruit 2.1 [4].
Fruit,until Version 2.1 open source, is a groundbreaking UCI compatible chess engine developed by primary author Fabien Letouzey. It made its first appearance to the public in March 2004, when Fruit was a basic program with a very simple evaluation and basic search. However, since then it made progress adding about 100 Elo to each new release (1.5, 2.0, 2.1 and Fruit 2.2) [2].
The release of Fruit until version 2.1 under the GNU General Public License was a "revolution" in computer chess in 2005 - an open source engine was "suddenly" competitive with the long time leading programs Shredder and Junior, as demonstrated at the WCCC 2005, where Fruit became runner up behind Zappa. After the strong Massy 2005 over the board debut, and the great success of Reykjavik, where Fabien Letouzey met his professional colleagues, he decided to close the source [3] and to go commercial [4] - while Fruit derivatives have already appeared based on the source code of Fruit 2.1, most notably Toga by Thomas Gaksch, and Gambit Fruit by Ryan Benitez, who in late 2005 joint forces with Fabian for the commercial endeavor. Fabien finished his commercial computer chess career so far in 2007 [5]. Fruit 2.3+ is non GPL with full rights given to Ryan Benitez who continued the Fruit development porting it to bitboards [6], while Fruit 2.1 is now owned by the Free Software Foundation [7], released as GNU Chess 6 [8].
Fruit was and still is one of the most influential didactic open source programs. It uses a 16x12 Vector attack board representation, since Version 1.5 a 16x16 board to have a symmetric treatment of files and ranks [10] . Its structure and C source code was very clean and apparently bug-free due to runtime checking a lot of preconditions using debug asserts. While late move reductions (LMR) might be used in other programs before, Fabien's history based implementation in conjunction with history leaf pruning made LMR very popular. Another Fruit innovation, despite not absolutely new and already a known issue, and related to what is mentioned in evaluation philosophy, was tapered evaluation to avoid discontinuity [11] .
Beside Fabien Letouzey as primary author and opening book author Marc Lacrosse, Ryan Benitez joined the Fruit-Team in December 2005. Before he developed Gambit Fruit with some interesting changes on the basis of the last open-source-version 2.1. Joachim Rang was the main tester of Fruit since its first public appearance, tuned parameters, and tested evaluation and search features [12] .
In March 2014, ten years after the initial Fruit 1.0 release, Daniel Mehrmann initiated a "let's update Fruit" called Fruit Reloaded [18]. With some help from Ryan Benitez, the aim is to add SMP to Fruit and upgrade search and evaluation with modern techniques [19] [20]. Simultaneously, Fabien Letouzey waved goodbye to Fruit and published his new open source engine Senpai, also with Ryan Benitez and Joachim Rang involved [21].
gnuchessMAC40b5.zip(176K) GNU Chess Mac 4.0b5 repackaged into a zipped hfs disk image and checksum file.The disk image can be mounted with Mini vMac.gnuchessMAC40b5.hqx(233K) GNU Chess Mac 4.0b5 in the original format.
gnuchessMAC-src-v40b5.zip(143K) GNU Chess Mac 4.0b5 Source repackaged into a zipped hfs disk image and checksum file.The disk image can be mounted with Mini vMac.gnuchessMAC-src-v40b5.hqx(213K) GNU Chess Mac 4.0b5 Source in the original format.
GNU Chess is a program that plays the ancient board game, Chess. It is licensed under the GPLv2. The original version of GNU Chess, written by Stuart Cracraft[1], was one of the first major games to be developed deliberately as free software. On the game Free Software Foundation founder Richard M. Stallman said "We even developed a chess game, GNU Chess, because a complete [free] system needs games too."[2] Version 6 of GNU Chess is based on[3] Fruit, a chess engine by Fabien Letouzey[1]
With Flatpak GNU Chess can be played by installing Sugarchess, a graphical front end made specifically for it.[4] A contemporary version was included on the 100 Great Games for Linux shovelware collection.
However, learning the basics is just the beginning. It takes time and practice to master the skills to handle the many possible variations in a game. Mathematician Claude Shannon calculated that there are 1043 possible legal moves in a chess game.
Like many classic games, chess is available as a computer application for almost every computing platform, including smartphones. This roundup includes seven different open source Android applications that chess enthusiasts should check out. With these apps you can play chess against your phone or an online opponent, study and analyze chess games, turn your phone into a basic chess clock, and even organize a chess tournament. All of these apps are in the F-Droid repository, which is an excellent resource for users who want to avoid the Google Play store, and only use purely open source software on their Android device.
Despite being simply named, Chess is the app on this list with the most features. The standard play mode includes features such playing in blind mode with the pieces hidden, and supports Chess 960-Fisher Random mode, which changes the starting locations of the pieces. In addition to play vs. computer, play vs. another person locally, and online play, Chess includes a puzzle mode and a practice mode. The puzzle mode challenges players with "Mate in Two" exercises, while the practice mode races the player against the clock. Users can download practice sets, a beginner puzzle set, and other add-ons from the Chess website. The version of the app in F-Droid has not been updated since 2014, but it is a mature, polished app. It is available under an MIT license, and source code is on GitHub.
Chess Walk is a simple, basic chess program. Players compete against a computer opponent, or against an online opponent via the Free Internet Chess Server. Beyond that, Chess Walk offers few extra features, and while it might not do as much as some of the other chess programs on this list, it is the perfect choice for a user looking for an lightweight app that does one thing and does it well. Chess Walk's source code is hosted on GitLab, and the app is licensed under the GPLv3.
DroidFish is built on the Cuckoochess and StockFish chess engines. It supports a wide variety of game modes, including two players playing on the same device, and two computer players playing each other. The app supports opening books and endgame tables, displays arrows showing possible moves, and has an analysis mode and a blind play mode. If Scid on the go (see below) is installed, DroidFish can read the Scid files, allowing the user to review chess games inside DroidFish. With so many features aimed at helping users study and improve their chess game, DroidFish is an excellent choice for a user wanting an app for digging deep into strategy.
Scid on the go is a mobile viewer for Shane's Chess Information Database files. These files are collections of chess games for study and review. The version of Scid on the go in F-Droid has not been updated since 2013, but the version in the Google Play Store has a version that was updated in May of 2015. Despite the fact that the F-Droid version is somewhat outdated, it can fetch and import files from The Week in Chess magazine with no problems, but it does seem to have issues connecting to ChessOK. Released under the GPLv2, Scid on the go's source code is hosted on Google Code, and there does not seem to be a more up-to-date repository.
ChessWatch is one of the two chess clock applications available in F-Droid. It turns an Android device into a impromptu chess clock, but it is not as nice as using a real chess clock. Use it to set the initial time on the clock, and the amount of time added to each player's time after each move. The clock uses the Fischer delay method for adding time to the clock. The button for ending a turn is very small, and most of the screen is just wasted space. ChessWatch's source code is available on GitHub, and the project uses the GPLv2. 2ff7e9595c
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