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Free Chess Engines

Chess engine – Wikipedia

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 no graphics nor windowing.Engines are usually used with a front end, a windowed graphical user interface such as Chessbase or WinBoard that the user can …

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Chess engine – Wikipedia

Lucas Chess


The program has 40 engines prepared to play from the start, and with very different levels, from 0 to 3300 elo.This list of engines is not closed and you can add other ones with the only limitation that they use the UCI protocol.The game can be set, limiting the depth of analysis of the motor or the time used to think, or by modifying the way in which it decides.You can also choose the opening, or start in a certain position, or that the engine uses a book of openings or more or less aid.Younger children will be able to begin their apprenticeship with special engines that know little more than moving the pieces, and this will enable them to win against the engines from the very beginning.


You have an extensive list of trainings with which to try to improve your chess: Training positions Play like a grandmaster Training mates Find best move Resistance Test Your daily test Learn tactics by repetition Learn openings by repetition Training with a book Long-term trainings Training on a map Transsiberian Railway Expeditions to the Everest Turn on the lights The Washing Machine Resources for zebras Check your memory on a chessboard Find all moves Becoming a knight tamer Moves between two positions Determine your calculating power Learn a game The board at a glance


In Lucas Chess there are several competitions, and in two of them you can publish the results.The first is a one-to-one competition against all the engines, starting with the weakest, initially in each engine many hints are available, and as you change level, the hints will be reduced.And in the second, Lucas-elo, where you can deal with all the engines in your range of score and add or subtract points according to the results of the games.

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Lucas Chess

Chess engine – Wikipedia

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 no graphics nor windowing.Engines are usually used with a front end, a windowed graphical user interface such as Chessbase or WinBoard that the user can …

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Chess engine – Wikipedia

Free Chess Engines

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Free Chess Engines

Lucas Chess


The program has 40 engines prepared to play from the start, and with very different levels, from 0 to 3300 elo.This list of engines is not closed and you can add other ones with the only limitation that they use the UCI protocol.The game can be set, limiting the depth of analysis of the motor or the time used to think, or by modifying the way in which it decides.You can also choose the opening, or start in a certain position, or that the engine uses a book of openings or more or less aid.Younger children will be able to begin their apprenticeship with special engines that know little more than moving the pieces, and this will enable them to win against the engines from the very beginning.


You have an extensive list of trainings with which to try to improve your chess: Training positions Play like a grandmaster Training mates Find best move Resistance Test Your daily test Learn tactics by repetition Learn openings by repetition Training with a book Long-term trainings Training on a map Transsiberian Railway Expeditions to the Everest Turn on the lights The Washing Machine Resources for zebras Check your memory on a chessboard Find all moves Becoming a knight tamer Moves between two positions Determine your calculating power Learn a game The board at a glance


In Lucas Chess there are several competitions, and in two of them you can publish the results.The first is a one-to-one competition against all the engines, starting with the weakest, initially in each engine many hints are available, and as you change level, the hints will be reduced.And in the second, Lucas-elo, where you can deal with all the engines in your range of score and add or subtract points according to the results of the games.

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Lucas Chess

Top 5 Best Chess Engines of the World in 2018 | iChess.NET

Conclusion Best Chess Engines. Chess engines are a curse and a blessing at the same time. Chess players who use them intelligently greatly benefit from the rise of strong computers. However, legitimate chess improvement requires a level of discipline that prefers to avoid shortcuts and opts for the steeper path to real knowledge and understanding.

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Top 5 Best Chess Engines of the World in 2018 | iChess.NET

Free Chess Engines

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Free Chess Engines

Chess Engines Diary

Brainfish – UCI chess engine, JCER Rating=3382 From the author: Brainfish is a standard Stockfish chess engine extended by a general book format that is capable of handling a reduced part of Cerebellum, which is an innovative chess opening and playing book. In Brainfish, the book moves are only used in engine games, not in analysis mode. All moves in the published book Cerebellum_light.bin …

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Chess Engines Diary

Universal Chess Interface – Wikipedia

A Universal Chess Interface (UCI) is an open communication protocol that enables chess engines to communicate with user interfaces.[1][2]

In November 2000, the UCI protocol was released. Designed by Rudolf Huber and Stefan Meyer-Kahlen, the author of Shredder, UCI rivals the older “Chess Engine Communication Protocol” introduced with XBoard/WinBoard.

In 2002, Chessbase, the chess software company which markets Fritz, began to support UCI, which had previously been supported by only a few interfaces and engines.

As of 2007[update], well over 100 engines are known to directly support UCI.

By design, UCI assigns some tasks to the user interface (i.e., presentation layer) which have traditionally been handled by the engine (at the business layer) itself.[citation needed]

Most notably, the opening book is usually expected to be handled by the UI, by simply selecting moves to play until it is out of book, and only then starting up the engine for calculation in the resulting position. UCI does not specify any on-disk format for the opening book. Different UIs usually have their own proprietary formats.[citation needed]

While the UI can also take responsibility for handling endgame tablebases, this is arguably better handled in the engine itself, as having tablebase information can be useful for considering possible future positions.[3]

Stefan-Meyer Kahlen’s UCI protocol in Shredder uses long algebraic notation for moves. A “nullmove” from the Engine to the GUI should be sent as 0000.[4]

The uci_limitstrength parameter tells engines with this feature to play at a lower level. The uci_elo parameter specifies the Elo rating at which the engine will aim to play.

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Universal Chess Interface – Wikipedia

Chess Engines Diary

Full acces to the folder: CHESS ENGINES – about 3000 files!If you do not want to wait a long time for download – donate a minimum of 10$, enter your email – you will gain full access to the folder with chess engines. Bonus on donate of 15$ – acces to the folder with games, tables, engines pack. My email: jotes@go2.pl

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Chess Engines Diary

Top Chess Engine Championship – Wikipedia

Top Chess Engine Championship, formerly known as Thoresen Chess Engines Competition (TCEC or nTCEC), is a computer chess tournament that has been run since 2010. It was organized, directed, and hosted by Martin Thoresen until the end of Season 6; from Season 7 onward it has been organized by Chessdom. It is often regarded as the Unofficial World Computer Chess Championship because of its strong participant line-up and long time-control matches on high-end hardware, giving rise to very high-class chess.[1][2]

After a short break in 2012,[3] TCEC was restarted in early 2013 (as nTCEC)[4] and is currently active (renamed as TCEC in early 2014) with 24/7 live broadcasts of chess matches on its website.

Since season 5, TCEC has been sponsored by Chessdom Arena.[5][6] The current TCEC champion is Stockfish 190203, which defeated LCZero v20.2-32930 by a score of 50.5-49.5 in the TCEC Season 14 Superfinal 100-game match held in February 2019.

The TCEC competition is divided into seasons, where each season happens over a course of a few months, with matches played round-the-clock and broadcast live over the internet. Each season is divided into several qualifying stages and one “superfinal”, where the top two chess engines play 100 games to win the title of “TCEC Grand Champion”. In the superfinal, each engine plays 50 openings, once as each side. Beginning in Season 11 in 2018, a division system was introduced; the top 2 engines in each division are promoted, and the bottom 2 are relegated. Currently there are 5 divisions (a Premier division, and divisions 1-4); newcomers generally start in division 4.

Pondering is set to off. All engines run on mostly the same hardware[7] and use the same opening book, which is set by the organizers and changed in every stage. Large pages are disabled but access to various endgame tablebases is permitted. Engines are allowed updates between stages; if there is a critical play-limiting bug, they are also allowed to be updated once during the stage. If an engine crashes 3 times in one event, it is disqualified to avoid distorting the results for the other engines. TCEC generates its own elo rating list from the matches played during the tournament. An initial rating is given to any new participant based on its rating in other chess engine rating lists.

There is no definite criterion for entering into the competition, other than inviting the top participants from various rating lists. Initially, the list of participants was personally chosen by Thoresen before the start of a season. His stated goal was to include “every major engine that is not a direct clone”.[8] However, Shredder’s developers have declined to enter it in the competition. Usually chess engines that support multiprocessor mode are preferred (8-cores or higher). Both Winboard and UCI engines are supported.

Shredder vs Gull, TCEC S4

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Top Chess Engine Championship – Wikipedia

Free Chess Engines

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Free Chess Engines

Lucas Chess


The program has 40 engines prepared to play from the start, and with very different levels, from 0 to 3300 elo.This list of engines is not closed and you can add other ones with the only limitation that they use the UCI protocol.The game can be set, limiting the depth of analysis of the motor or the time used to think, or by modifying the way in which it decides.You can also choose the opening, or start in a certain position, or that the engine uses a book of openings or more or less aid.Younger children will be able to begin their apprenticeship with special engines that know little more than moving the pieces, and this will enable them to win against the engines from the very beginning.


You have an extensive list of trainings with which to try to improve your chess: Training positions Play like a grandmaster Training mates Find best move Resistance Test Your daily test Learn tactics by repetition Learn openings by repetition Training with a book Long-term trainings Training on a map Transsiberian Railway Expeditions to the Everest Turn on the lights The Washing Machine Resources for zebras Check your memory on a chessboard Find all moves Becoming a knight tamer Moves between two positions Determine your calculating power Learn a game The board at a glance


In Lucas Chess there are several competitions, and in two of them you can publish the results.The first is a one-to-one competition against all the engines, starting with the weakest, initially in each engine many hints are available, and as you change level, the hints will be reduced.And in the second, Lucas-elo, where you can deal with all the engines in your range of score and add or subtract points according to the results of the games.

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Lucas Chess

Chess Engines Diary

Full acces to the folder: CHESS ENGINES – about 3000 files!If you do not want to wait a long time for download – donate a minimum of 10$, enter your email – you will gain full access to the folder with chess engines. Bonus on donate of 15$ – acces to the folder with games, tables, engines pack. My email: jotes@go2.pl

See the article here:

Chess Engines Diary

Computer chess – Wikipedia

Computer hardware and software capable of playing chess

Computer chess includes both hardware (dedicated computers) and software capable of playing chess. Computer chess provides opportunities for players to practice even in the absence of human opponents, and also provides opportunities for analysis, entertainment and training. Since around 2005, chess engines have been able to defeat even the strongest human players. Nevertheless, it is considered unlikely that computers will ever solve chess due to its computational complexity.

The idea of creating a chess-playing machine dates back to the eighteenth century. Around 1769, the chess playing automaton called The Turk became famous before being exposed as a hoax. Before the development of digital computing, serious trials based on automata such as El Ajedrecista of 1912, were too complex and limited to be useful for playing full games of chess. The field of mechanical chess research languished until the advent of the digital computer in the 1950s. Since then, chess enthusiasts and computer engineers have built, with increasing degrees of seriousness and success, chess-playing machines and computer programs.

Chess-playing computers and software came onto the market in the mid-1970s. There are many chess engines such as Stockfish, Crafty, Fruit and GNU Chess that can be downloaded from the Internet free of charge. Top programs such as Stockfish have surpassed even world champion caliber players.

CEGT,[42] CSS,[43] SSDF,[44] and WBEC[45] maintain rating lists allowing fans to compare the strength of engines. As of 3 February 2016, Stockfish is the top rated chess program on the IPON rating list.[46]

CCRL (Computer Chess Rating Lists) is an organisation that tests computer chess engines’ strength by playing the programs against each other. CCRL was founded in 2006 by Graham Banks, Ray Banks, Sarah Bird, Kirill Kryukov and Charles Smith, and as of June 2012 its members are Graham Banks, Ray Banks (who only participates in Chess960, or Fischer Random Chess), Shaun Brewer, Adam Hair, Aser Huerga, Kirill Kryukov, Denis Mendoza, Charles Smith and Gabor Szots.[47]

The organisation runs three different lists: 40/40 (40 minutes for every 40 moves played), 40/4 (4 minutes for every 40 moves played), and 40/4 FRC (same time control but Chess960).[Note 1] Pondering (or permanent brain) is switched off and timing is adjusted to the AMD64 X2 4600+ (2.4 GHz) CPU by using Crafty 19.17 BH as a benchmark. Generic, neutral opening books are used (as opposed to the engine’s own book) up to a limit of 12 moves into the game alongside 4 or 5 man tablebases.[47][48][49]

Using “ends-and-means” heuristics a human chess player can intuitively determine optimal outcomes and how to achieve them regardless of the number of moves necessary, but a computer must be systematic in its analysis. Most players agree that looking at least five moves ahead (ten plies) when necessary is required to play well. Normal tournament rules give each player an average of three minutes per move. On average there are more than 30 legal moves per chess position, so a computer must examine a quadrillion possibilities to look ahead ten plies (five full moves); one that could examine a million positions a second would require more than 30 years.[50]

After discovering refutation screeningthe application of alpha-beta pruning to optimizing move evaluationin 1957, a team at Carnegie Mellon University predicted that a computer would defeat the world human champion by 1967.[51] It did not anticipate the difficulty of determining the right order to evaluate branches. Researchers worked to improve programs’ ability to identify killer heuristics, unusually high-scoring moves to reexamine when evaluating other branches, but into the 1970s most top chess players believed that computers would not soon be able to play at a Master level.[50] In 1968 International Master David Levy made a famous bet that no chess computer would be able to beat him within ten years,[6] and in 1976 Senior Master and professor of psychology Eliot Hearst of Indiana University wrote that “the only way a current computer program could ever win a single game against a master player would be for the master, perhaps in a drunken stupor while playing 50 games simultaneously, to commit some once-in-a-year blunder”.[50]

In the late 1970s chess programs suddenly began defeating top human players.[50] The year of Hearst’s statement, Northwestern University’s Chess 4.5 at the Paul Masson American Chess Championship’s Class B level became the first to win a human tournament. Levy won his bet in 1978 by beating Chess 4.7, but it achieved the first computer victory against a Master-class player at the tournament level by winning one of the six games.[6] In 1980 Belle began often defeating Masters. By 1982 two programs played at Master level and three were slightly weaker.[50]

The sudden improvement without a theoretical breakthrough surprised humans, who did not expect that Belle’s ability to examine 100,000 positions a secondabout eight plieswould be sufficient. The Spracklens, creators of the successful microcomputer program Sargon, estimated that 90% of the improvement came from faster evaluation speed and only 10% from improved evaluations. New Scientist stated in 1982 that computers “play terrible chess … clumsy, inefficient, diffuse, and just plain ugly”, but humans lost to them by making “horrible blunders, astonishing lapses, incomprehensible oversights, gross miscalculations, and the like” much more often than they realized; “in short, computers win primarily through their ability to find and exploit miscalculations in human initiatives”.[50]

By 1982, microcomputer chess programs could evaluate up to 1,500 moves a second and were as strong as mainframe chess programs of five years earlier, able to defeat almost all players. While only able to look ahead one or two plies more than at their debut in the mid-1970s, doing so improved their play more than experts expected; seemingly minor improvements “appear to have allowed the crossing of a psychological threshold, after which a rich harvest of human error becomes accessible”, New Scientist wrote.[50] While reviewing SPOC in 1984, BYTE wrote that “Computersmainframes, minis, and microstend to play ugly, inelegant chess”, but noted Robert Byrne’s statement that “tactically they are freer from error than the average human player”. The magazine described SPOC as a “state-of-the-art chess program” for the IBM PC with a “surprisingly high” level of play, and estimated its USCF rating as 1700 (Class B).[52]

At the 1982 North American Computer Chess Championship, Monroe Newborn predicted that a chess program could become world champion within five years; tournament director and International Master Michael Valvo predicted ten years; the Spracklens predicted 15; Ken Thompson predicted more than 20; and others predicted that it would never happen. The most widely held opinion, however, stated that it would occur around the year 2000.[53] In 1989, Levy was defeated by Deep Thought in an exhibition match. Deep Thought, however, was still considerably below World Championship Level, as the then reigning world champion Garry Kasparov demonstrated in two strong wins in 1989. It was not until a 1996 match with IBM’s Deep Blue that Kasparov lost his first game to a computer at tournament time controls in Deep Blue – Kasparov, 1996, Game 1. This game was, in fact, the first time a reigning world champion had lost to a computer using regular time controls. However, Kasparov regrouped to win three and draw two of the remaining five games of the match, for a convincing victory.

In May 1997, an updated version of Deep Blue defeated Kasparov 32 in a return match. A documentary mainly about the confrontation was made in 2003, titled Game Over: Kasparov and the Machine. IBM keeps a web site of the event.

With increasing processing power and improved evaluation functions, chess programs running on commercially available workstations began to rival top flight players. In 1998, Rebel 10 defeated Viswanathan Anand, who at the time was ranked second in the world, by a score of 53. However most of those games were not played at normal time controls. Out of the eight games, four were blitz games (five minutes plus five seconds Fischer delay (see time control) for each move); these Rebel won 31. Two were semi-blitz games (fifteen minutes for each side) that Rebel won as well (1). Finally, two games were played as regular tournament games (forty moves in two hours, one hour sudden death); here it was Anand who won 1.[54] In fast games, computers played better than humans, but at classical time controls at which a player’s rating is determined the advantage was not so clear.

In the early 2000s, commercially available programs such as Junior and Fritz were able to draw matches against former world champion Garry Kasparov and classical world champion Vladimir Kramnik.

In October 2002, Vladimir Kramnik and Deep Fritz competed in the eight-game Brains in Bahrain match, which ended in a draw. Kramnik won games 2 and 3 by “conventional” anti-computer tactics play conservatively for a long-term advantage the computer is not able to see in its game tree search. Fritz, however, won game 5 after a severe blunder by Kramnik. Game 6 was described by the tournament commentators as “spectacular.” Kramnik, in a better position in the early middlegame, tried a piece sacrifice to achieve a strong tactical attack, a strategy known to be highly risky against computers who are at their strongest defending against such attacks. True to form, Fritz found a watertight defense and Kramnik’s attack petered out leaving him in a bad position. Kramnik resigned the game, believing the position lost. However, post-game human and computer analysis has shown that the Fritz program was unlikely to have been able to force a win and Kramnik effectively sacrificed a drawn position. The final two games were draws. Given the circumstances, most commentators still rate Kramnik the stronger player in the match.[citation needed]

In January 2003, Garry Kasparov played Junior, another chess computer program, in New York City. The match ended 33.

In November 2003, Garry Kasparov played X3D Fritz. The match ended 22.

In 2005, Hydra, a dedicated chess computer with custom hardware and sixty-four processors and also winner of the 14th IPCCC in 2005, defeated seventh-ranked Michael Adams 5 in a six-game match (though Adams’ preparation was far less thorough than Kramnik’s for the 2002 series).[55]

In NovemberDecember 2006, World Champion Vladimir Kramnik played Deep Fritz. This time the computer won; the match ended 24. Kramnik was able to view the computer’s opening book. In the first five games Kramnik steered the game into a typical “anti-computer” positional contest. He lost one game (overlooking a mate in one), and drew the next four. In the final game, in an attempt to draw the match, Kramnik played the more aggressive Sicilian Defence and was crushed.

There was speculation that interest in human-computer chess competition would plummet as a result of the 2006 Kramnik-Deep Fritz match.[56] According to Newborn, for example, “the science is done”.[57]

Human-computer chess matches showed the best computer systems overtaking human chess champions in the late 1990s. For the 40 years prior to that, the trend had been that the best machines gained about 40 points per year in the Elo rating while the best humans only gained roughly 2 points per year.[58] The highest rating obtained by a computer in human competition was Deep Thought’s USCF rating of 2551 in 1988 and FIDE no longer accepts human-computer results in their rating lists. Specialized machine-only Elo pools have been created for rating machines, but such numbers, while similar in appearance, should not be directly compared.[59] In 2016, the Swedish Chess Computer Association rated computer program Komodo at 3361.

Chess engines continue to improve. In 2009, chess engines running on slower hardware have reached the grandmaster level. A mobile phone won a category 6 tournament with a performance rating 2898: chess engine Hiarcs 13 running inside Pocket Fritz 4 on the mobile phone HTC Touch HD won the Copa Mercosur tournament in Buenos Aires, Argentina with 9 wins and 1 draw on August 414, 2009.[33] Pocket Fritz 4 searches fewer than 20,000 positions per second.[60] This is in contrast to supercomputers such as Deep Blue that searched 200 million positions per second.

Advanced Chess is a form of chess developed in 1998 by Kasparov where a human plays against another human, and both have access to computers to enhance their strength. The resulting “advanced” player was argued by Kasparov to be stronger than a human or computer alone, this has been proven in numerous occasions, at Freestyle Chess events. In 2017, a win by a computer engine in the freestyle Ultimate Challenge tournament.[41] was the source of a lengthy debate, in which the organisers declined to participate.

Players today are inclined to treat chess engines as analysis tools rather than opponents.[61]

The developers of a chess-playing computer system must decide on a number of fundamental implementation issues. These include:

Computer chess programs usually support a number of common de facto standards. Nearly all of today’s programs can read and write game moves as Portable Game Notation (PGN), and can read and write individual positions as ForsythEdwards Notation (FEN). Older chess programs often only understood long algebraic notation, but today users expect chess programs to understand standard algebraic chess notation.

Starting in the late 1990s, programmers began to develop separately engines (with a command-line interface which calculates which moves are strongest in a position) or a graphical user interface(GUI) which provides the player with a chessboard they can see, and pieces that can be moved. Engines communicate their moves to the GUI using a protocol such as the Chess Engine Communication Protocol (CECP) or Universal Chess Interface (UCI). By dividing chess programs into these two pieces, developers can write only the user interface, or only the engine, without needing to write both parts of the program. (See also chess engines.)

Developers have to decide whether to connect the engine to an opening book and/or endgame tablebases or leave this to the GUI.

The data structure used to represent each chess position is key to the performance of move generation and position evaluation. Methods include pieces stored in an array (“mailbox” and “0x88”), piece positions stored in a list (“piece list”), collections of bit-sets for piece locations (“bitboards”), and huffman coded positions for compact long-term storage.

The first paper on the subject was by Claude Shannon in 1950.[62] He predicted the two main possible search strategies which would be used, which he labeled “Type A” and “Type B”,[63] before anyone had programmed a computer to play chess.

Type A programs would use a “brute force” approach, examining every possible position for a fixed number of moves using the minimax algorithm. Shannon believed this would be impractical for two reasons.

First, with approximately thirty moves possible in a typical real-life position, he expected that searching the approximately 109 positions involved in looking three moves ahead for both sides (six plies) would take about sixteen minutes, even in the “very optimistic” case that the chess computer evaluated a million positions every second. (It took about forty years to achieve this speed.)

Second, it ignored the problem of quiescence, trying to only evaluate a position that is at the end of an exchange of pieces or other important sequence of moves (‘lines’). He expected that adapting type A to cope with this would greatly increase the number of positions needing to be looked at and slow the program down still further.

Instead of wasting processing power examining bad or trivial moves, Shannon suggested that “type B” programs would use two improvements:

This would enable them to look further ahead (‘deeper’) at the most significant lines in a reasonable time. The test of time has borne out the first approach; all modern programs employ a terminal quiescence search before evaluating positions. The second approach (now called forward pruning) has been dropped in favor of search extensions.

Adriaan de Groot interviewed a number of chess players of varying strengths, and concluded that both masters and beginners look at around forty to fifty positions before deciding which move to play. What makes the former much better players is that they use pattern recognition skills built from experience. This enables them to examine some lines in much greater depth than others by simply not considering moves they can assume to be poor.

More evidence for this being the case is the way that good human players find it much easier to recall positions from genuine chess games, breaking them down into a small number of recognizable sub-positions, rather than completely random arrangements of the same pieces. In contrast, poor players have the same level of recall for both.

The problem with type B is that it relies on the program being able to decide which moves are good enough to be worthy of consideration (‘plausible’) in any given position and this proved to be a much harder problem to solve than speeding up type A searches with superior hardware and search extension techniques.

One of the few chess grandmasters to devote himself seriously to computer chess was former World Chess Champion Mikhail Botvinnik, who wrote several works on the subject. He also held a doctorate in electrical engineering. Working with relatively primitive hardware available in the Soviet Union in the early 1960s, Botvinnik had no choice but to investigate software move selection techniques; at the time only the most powerful computers could achieve much beyond a three-ply full-width search, and Botvinnik had no such machines. In 1965 Botvinnik was a consultant to the ITEP team in a US-Soviet computer chess match (see Kotok-McCarthy).

One developmental milestone occurred when the team from Northwestern University, which was responsible for the Chess series of programs and won the first three ACM Computer Chess Championships (197072), abandoned type B searching in 1973. The resulting program, Chess 4.0, won that year’s championship and its successors went on to come in second in both the 1974 ACM Championship and that year’s inaugural World Computer Chess Championship, before winning the ACM Championship again in 1975, 1976 and 1977.

One reason they gave for the switch was that they found it less stressful during competition, because it was difficult to anticipate which moves their type B programs would play, and why. They also reported that type A was much easier to debug in the four months they had available and turned out to be just as fast: in the time it used to take to decide which moves were worthy of being searched, it was possible just to search all of them.

In fact, Chess 4.0 set the paradigm that was and still is followed essentially by all modern Chess programs today. Chess 4.0 type programs won out for the simple reason that their programs played better chess. Such programs did not try to mimic human thought processes, but relied on full width alpha-beta and negascout searches. Most such programs (including all modern programs today) also included a fairly limited selective part of the search based on quiescence searches, and usually extensions and pruning (particularly null move pruning from the 1990s onwards) which were triggered based on certain conditions in an attempt to weed out or reduce obviously bad moves (history moves) or to investigate interesting nodes (e.g. check extensions, passed pawns on seventh rank, etc.). Extension and pruning triggers have to be used very carefully however. Over extend and the program wastes too much time looking at uninteresting positions. If too much is pruned, there is a risk cutting out interesting nodes. Chess programs differ in terms of how and what types of pruning and extension rules are included as well as in the evaluation function. Some programs are believed to be more selective than others (for example Deep Blue was known to be less selective than most commercial programs because they could afford to do more complete full width searches), but all have a base full width search as a foundation and all have some selective components (Q-search, pruning/extensions).

Though such additions meant that the program did not truly examine every node within its search depth (so it would not be truly brute force in that sense), the rare mistakes due to these selective searches was found to be worth the extra time it saved because it could search deeper. In that way Chess programs can get the best of both worlds.

Furthermore, technological advances by orders of magnitude in processing power have made the brute force approach far more incisive than was the case in the early years. The result is that a very solid, tactical AI player aided by some limited positional knowledge built in by the evaluation function and pruning/extension rules began to match the best players in the world. It turned out to produce excellent results, at least in the field of chess, to let computers do what they do best (calculate) rather than coax them into imitating human thought processes and knowledge. In 1997 Deep Blue defeated World Champion Garry Kasparov, marking the first time a computer has defeated a reigning world chess champion in standard time control.

Computer chess programs consider chess moves as a game tree. In theory, they examine all moves, then all counter-moves to those moves, then all moves countering them, and so on, where each individual move by one player is called a “ply”. This evaluation continues until a certain maximum search depth or the program determines that a final “leaf” position has been reached (e.g. checkmate).

A naive implementation of this approach can only search to a small depth in a practical amount of time, so various methods have been devised to greatly speed the search for good moves.

The AlphaZero program uses a variant of Monte Carlo tree search without rollout.[64]

For more information, see:

For most chess positions, computers cannot look ahead to all possible final positions. Instead, they must look ahead a few plies and compare the possible positions, known as leaves. The algorithm that evaluates leaves is termed the “evaluation function”, and these algorithms are often vastly different between different chess programs.

Evaluation functions typically evaluate positions in hundredths of a pawn (called a centipawn), and consider material value along with other factors affecting the strength of each side. When counting up the material for each side, typical values for pieces are 1 point for a pawn, 3 points for a knight or bishop, 5 points for a rook, and 9 points for a queen. (See Chess piece relative value.) The king is sometimes given an arbitrary high value such as 200 points (Shannon’s paper) or 1,000,000,000 points (1961 USSR program) to ensure that a checkmate outweighs all other factors (Levy & Newborn 1991:45). By convention, a positive evaluation favors White, and a negative evaluation favors Black.

In addition to points for pieces, most evaluation functions take many factors into account, such as pawn structure, the fact that a pair of bishops are usually worth more, centralized pieces are worth more, and so on. The protection of kings is usually considered, as well as the phase of the game (opening, middle or endgame).

Endgame play had long been one of the great weaknesses of chess programs, because of the depth of search needed. Some otherwise master-level programs were unable to win in positions where even intermediate human players can force a win.

To solve this problem, computers have been used to analyze some chess endgame positions completely, starting with king and pawn against king. Such endgame tablebases are generated in advance using a form of retrograde analysis, starting with positions where the final result is known (e.g., where one side has been mated) and seeing which other positions are one move away from them, then which are one move from those, etc. Ken Thompson was a pioneer in this area.

The results of the computer analysis sometimes surprised people. In 1977 Thompson’s Belle chess machine used the endgame tablebase for a king and rook against king and queen and was able to draw that theoretically lost ending against several masters (see Philidor position#Queen versus rook). This was despite not following the usual strategy to delay defeat by keeping the defending king and rook close together for as long as possible. Asked to explain the reasons behind some of the program’s moves, Thompson was unable to do so beyond saying the program’s database simply returned the best moves.

Most grandmasters declined to play against the computer in the queen versus rook endgame, but Walter Browne accepted the challenge. A queen versus rook position was set up in which the queen can win in thirty moves, with perfect play. Browne was allowed 2 hours to play fifty moves, otherwise a draw would be claimed under the fifty-move rule. After forty-five moves, Browne agreed to a draw, being unable to force checkmate or win the rook within the next five moves. In the final position, Browne was still seventeen moves away from checkmate, but not quite that far away from winning the rook. Browne studied the endgame, and played the computer again a week later in a different position in which the queen can win in thirty moves. This time, he captured the rook on the fiftieth move, giving him a winning position (Levy & Newborn 1991:14448), (Nunn 2002:49).

Other positions, long believed to be won, turned out to take more moves against perfect play to actually win than were allowed by chess’s fifty-move rule. As a consequence, for some years the official FIDE rules of chess were changed to extend the number of moves allowed in these endings. After a while, the rule reverted to fifty moves in all positions more such positions were discovered, complicating the rule still further, and it made no difference in human play, as they could not play the positions perfectly.

Over the years, other endgame database formats have been released including the Edward Tablebase, the De Koning Database and the Nalimov Tablebase which is used by many chess programs such as Rybka, Shredder and Fritz. Tablebases for all positions with six pieces are available.[65] Some seven-piece endgames have been analyzed by Marc Bourzutschky and Yakov Konoval.[66] Programmers using the Lomonosov supercomputers in Moscow have completed a chess tablebase for all endgames with seven pieces or fewer (trivial endgame positions are excluded, such as six white pieces versus a lone black king).[67][68] In all of these endgame databases it is assumed that castling is no longer possible.

Many tablebases do not consider the fifty-move rule, under which a game where fifty moves pass without a capture or pawn move can be claimed to be a draw by either player. This results in the tablebase returning results such as “Forced mate in sixty-six moves” in some positions which would actually be drawn because of the fifty-move rule. One reason for this is that if the rules of chess were to be changed once more, giving more time to win such positions, it will not be necessary to regenerate all the tablebases. It is also very easy for the program using the tablebases to notice and take account of this ‘feature’ and in any case if using an endgame tablebase will choose the move that leads to the quickest win (even if it would fall foul of the fifty-move rule with perfect play). If playing an opponent not using a tablebase, such a choice will give good chances of winning within fifty moves.

The Nalimov tablebases, which use state-of-the-art compression techniques, require 7.05 GB of hard disk space for all five-piece endings. To cover all the six-piece endings requires approximately 1.2 TB. It is estimated that a seven-piece tablebase requires between 50 and 200 TB of storage space.[69]

Endgame databases featured prominently in 1999, when Kasparov played an exhibition match on the Internet against the rest of the world. A seven piece Queen and pawn endgame was reached with the World Team fighting to salvage a draw. Eugene Nalimov helped by generating the six piece ending tablebase where both sides had two Queens which was used heavily to aid analysis by both sides.

Many other optimizations can be used to make chess-playing programs stronger. For example, transposition tables are used to record positions that have been previously evaluated, to save recalculation of them. Refutation tables record key moves that “refute” what appears to be a good move; these are typically tried first in variant positions (since a move that refutes one position is likely to refute another). Opening books aid computer programs by giving common openings that are considered good play (and good ways to counter poor openings). Many chess engines use pondering to increase their strength.

Of course, faster hardware and additional processors can improve chess-playing program abilities, and some systems (such as Deep Blue) use specialized chess hardware instead of only software. Another way to examine more chess positions is to distribute the analysis of positions to many computers. The ChessBrain project[70] was a chess program that distributed the search tree computation through the Internet. In 2004 the ChessBrain played chess using 2,070 computers.

It has been estimated that doubling the computer speed gains approximately fifty to seventy Elo points in playing strength (Levy & Newborn 1991:192).

Chess engines have been developed to play some chess variants such as Capablanca Chess, but the engines are almost never directly integrated with specific hardware. Even for the software that has been developed, most will not play chess beyond a certain board size, so games played on an unbounded chessboard (infinite chess) remain virtually untouched by both chess computers and software.

These chess playing systems include custom hardware or run on supercomputers.

In the 1980s and early 1990s, there was a competitive market for dedicated chess computers. This market changed in the mid-90s when computers with dedicated processors could no longer compete with the fast processors in personal computers. Nowadays, most dedicated units sold are of beginner and intermediate strength.

Recently, some hobbyists have been using the Multi Emulator Super System to run the chess programs created for Fidelity or Hegener & Glaser’s Mephisto computers on modern 64 bit operating systems such as Windows 10.[72] The author of Rebel, Ed Schrder has also adapted three of the Hegener & Glaser Mephisto’s he wrote to work as UCI engines.[73]

These chess programs run on obsolete hardware:

These programs can be run on MS-DOS, and can be run on 64 bit Windows 10 via emulators such as DOSBox or Qemu:[75]

Perhaps the most common type of chess software are programs that simply play chess. You make a move on the board, and the AI calculates and plays a response, and back and forth until one player resigns. Sometimes the chess engine, which calculates the moves, and the graphical user interface(GUI) are separate programs. A variety of engines can be imported into the GUI, so that you can play against different styles. Engines often have just a simple text command-line interface while GUIs may offer a variety of piece sets, board styles or even 3D or animated pieces. Because recent engines are so strong, engines or GUIs may offer some way of limiting the engine’s strength, so the player has a better chance of winning. Universal Chess Interface(UCI) engines such Fritz or Rybka may have a built in mechanism for reducing the Elo rating of the engine (via UCI’s uci_limitstrength and uci_elo parameters). Some versions of Fritz have a Handicap and Fun mode for limiting the current engine or changing the percentage of mistakes it makes or changing its style. Fritz also has a Friend Mode where during the game it tries to match the level of the player.

Chess databases allow users to search through a large library of historical games, analyze them, check statistics, and draw up an opening repertoire. Chessbase (for PC) is perhaps the most common program for this amongst professional players, but there are alternatives such as Shane’s Chess Information Database (Scid) [76] for Windows, Mac or Linux, Chess Assistant[77] for PC,[78] Gerhard Kalab’s Chess PGN Master for Android[79] or Giordano Vicoli’s Chess-Studio for iOS.[80]

Programs such as Playchess allow you to play games against other players over the internet.

Chess training programs teach chess. Chessmaster had playthrough tutorials by IM Josh Waitzkin and GM Larry Christiansen. Stefan Meyer-Kahlen offers Shredder Chess Tutor based on the Step coursebooks of Rob Brunia and Cor Van Wijgerden. World champions Magnus Carlsen’s Play Magnus company recently released a Magnus Trainer app for Android and iOS. Chessbase has Fritz and Chesster for children. Convekta has a large number of training apps such as CT-ART and its Chess King line based on tutorials by GM Alexander Kalinin and Maxim Blokh.

There is also Software for handling chess problems.

Well-known computer chess theorists include:

The prospects of completely solving chess are generally considered to be rather remote. It is widely conjectured that there is no computationally inexpensive method to solve chess even in the very weak sense of determining with certainty the value of the initial position, and hence the idea of solving chess in the stronger sense of obtaining a practically usable description of a strategy for perfect play for either side seems unrealistic today. However, it has not been proven that no computationally cheap way of determining the best move in a chess position exists, nor even that a traditional alpha-beta-searcher running on present-day computing hardware could not solve the initial position in an acceptable amount of time. The difficulty in proving the latter lies in the fact that, while the number of board positions that could happen in the course of a chess game is huge (on the order of at least 1043[82] to 1047), it is hard to rule out with mathematical certainty the possibility that the initial position allows either side to force a mate or a threefold repetition after relatively few moves, in which case the search tree might encompass only a very small subset of the set of possible positions. It has been mathematically proven that generalized chess (chess played with an arbitrarily large number of pieces on an arbitrarily large chessboard) is EXPTIME-complete,[83] meaning that determining the winning side in an arbitrary position of generalized chess provably takes exponential time in the worst case; however, this theoretical result gives no lower bound on the amount of work required to solve ordinary 8×8 chess.

Gardner’s Minichess, played on a 55 board with approximately 1018 possible board positions, has been solved; its game-theoretic value is 1/2 (i.e. a draw can be forced by either side), and the forcing strategy to achieve that result has been described.

Progress has also been made from the other side: as of 2012, all 7 and fewer piece (2 kings and up to 5 other pieces) endgames have been solved.

A “chess engine” is software that calculates and orders which moves are the strongest to play in a given position. Engine authors focus on improving the play of their engines, often just importing the engine into a graphical user interface(GUI) developed by someone else. Engines communicate with the GUI by following standardized protocols such as the Universal Chess Interface developed by Stefan Meyer-Kahlen and Franz Huber or the Chess Engine Communication Protocol developed by Tim Mann for GNU Chess and Winboard. Chessbase has its own proprietary protocol, and at one time Millennium 2000 had another protocol used for ChessGenius. Engines designed for one operating system and protocol may be ported to other OS’s or protocols.

In 1997, the Internet Chess Club released its first Java client for playing chess online against other people inside one’s webbrowser.[84] This was probably one of the first chess web apps. Free Internet Chess Server followed soon after with a similar client.[85] In 2004, International Correspondence Chess Federation opened up a web server to replace their email based system.[86] Chess.com started offering Live Chess in 2007.[87] Chessbase/Playchess had long had a downloadable client, but they had a web interface by 2013.[88]

Another popular web app is tactics training. The now defunct Chess Tactics Server opened its site in 2006,[89] followed by Chesstempo the next year,[90] and Chess.com added its Tactics Trainer in 2008.[91] Chessbase added a tactics trainer web app in 2015.[92]

Chessbase took their chess game database online in 1998.[93] Another early chess game databases was Chess Lab, which started in 1999.[94] New In Chess had initially tried to compete with Chessbase by releasing a NICBase program for Windows 3.x, but eventually, decided to give up on software, and instead focus on their online database starting in 2002.[95]

One could play against the engine Shredder online from 2006.[96] In 2015, Chessbase added a play Fritz web app,[97] as well as My Games for storing one’s games.[98]

Starting in 2007, Chess.com offered the content of the training program, Chess Mentor, to their customers online. [99] Top GMs such as Sam Shankland and Walter Browne have contributed lessons.


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Computer chess – Wikipedia

Free Chess Engines

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Free Chess Engines

Stockfish – Official Site


Stockfish is one of the strongest chess engines in the world. It is also much stronger than the best human chess grandmasters.

Unlike most chess engines, Stockfish is open source (GPL license). That means you can read the code, modify it, contribute back, and even use it in your own projects.

You can use Stockfish on your computer running Windows, OS X, or Linux, or on your iOS or Android device. So you can get world-class chess analysis, wherever you are.

Read more here:

Stockfish – Official Site

Download free Chess Engines – Komodo 11, Houdini

Chess engine is the unique software which is built into the program shell (e.g. “Fritz”, “Arena”, “Shredder”) thus multiplying the force of the game shell. For example, “Kasparov Chess” is very good and clever shell. The maximum rating which can be set in it is 2600. And the rating of the chess engines reaches 3000-3200. That is why the chess engines are so popular. Where do the chess engines originate from and who makes them? This question is not trivial, vice versa it is quite actual, so it is worth talking about.

The first record of the chess engine was made about 20 years ago. That was just the time when the UCI standard was developed – the universal chess interface, allowing the chess engine to be connected to the graphic interface of the program shell. The engine made to this standard can be easily connected to any chess program. The standard was worked out by Stephan Meyer-Kahlen, German programmer, who was born in 1968 in Dusseldorf. He is also the founder of one of the most famous chess programs – Shredder, which is the 12-times world champion among chess machines. The UCI standard was presented to the world by Rudolf Huber. The standard has great advantages. For example, if the engine does not save the database of the games played (although it is better if this task is performed by the engine), then one can easily manage this database by UCI. As the UCI protocol is absolutely free, it gives it the advantage over the other protocols. It can be used for private purposes and as the open-source as well. This protocol was used by only a few programs until Chessbase Company (producing Fritz) began to support this protocol in 2002. Nowadays, this protocol is used by about 100 chess programs.

The majority of the chess engines are made very thoroughly and published in the net absolutely free of charge. In Russia there are the developers making engines, as well. E.g. SmarThink developed by Sergey Markov, GreKo developed by Vladimir Medvedev, Strelka developed by Yuri Osipov. These engines, as well as many others, can be downloaded from our website. As the number of the chess engines is growing, we chose the best ones, as there is simply no possibility to present all of them here.

Komodo 11 Version Windows 64

Komodo 10 2016 – Developer Mark Lefler. Version for Android, Linux, OSX, Windows ALL.

Houdini – Developer Robert Blow (Belgium). Houdini 6 x64 x32 UCI

Houdini – Developer Robert Blow (Belgium). 5.01 UCI Chess Engines [Full]

Komodo 8 – Champions 2015 – Developer Mark Lefler. Version for Android, Linux, OSX, Windows 7, 8 (32/64).

Houdini 4 PRO – Developer Robert Blow (Belgium). Version 4 PRO.

Houdini 2.0 – Developer Robert Blow (Belgium). Version 2.0. To date, the best engine. And you can Download Houdini 2.0 for a direct link.

Deep Rybka 4 – developer Vas Rajlich. Version 4 (w32)

Stockfish – Developers Tord Romstad, Marco Kostalba Kiiski and Joon. Version 2.11

Critter – Developer Richard Vida. Version 1.1.37

Naum – Developer Alexander Naumov (Canada). Version 4.2

Spark – Version 1.0

WildCat – Developer Igor Korshunov (Belarus). Version 8.0

SmarThink – Developer Sergei Markov (Russia). Version 0.17a

SOS – Designer Rudolf Huber (Germany). Version 11.99

Zchess – Designer Franck Zibi (France). Version 2.22

Gromit – Developers Frank Schneider and Kai Skibbe (Germany). Version 3.0

Ufim – Developer Niaz Hasanov (Russia). Version 8.2

Mustang – Developer Alex Korneichuk (Belarus). Version 4.97

GreKo – Developer Vladimir Medvedev (Russia). Version 8.2 + sour

Kaissa2 – Developer Vladimir Elin (Belarus). Version 1.8a

Adamant – Developer George Varentsov (Russia). Version 1.7

Booot – Developer of Alexei Morozov (Ukraine). Version 5.1.0 + sources

Eeyore – Developer Meidel Anton (Russia). Version 1.52 (32 & 64bit)

Zeus – Developer Vadim Bykov (Russia). Version 1.29

Arics – Developer Vladimir Fadeev (Belarus). Version 0.95a

Anechka – Developer Sergey Nefedov (Russia). Version 0.08

Patriot – Developer Vladimir Elin (Belarus). Version 2006

AlChess – Developer Alex Lobanov (Russia). Version 1.5b

OBender – Designer Evgeny Kornilov (Russia). Version 3.2.4x

Counter – Developer Vadim Chizhov (Russia). Version 1.2

Strelka – Designer Yuri Osipov (Russia). Version 2.0B + sources

Belka – Developers Yuri Osipov, Igor Korshunov (Russia – Belarus). Version 1.8.20

Ifrit – Developer Brenkman Andrew (Russia). Version 4.4 + source

Bison – Developer Ivan Bonkin (Russia). Version 9.11 + sour

Uralochka – Developer Ivan Maklyakov (Russia). Version 1.1b

Marginal – Designer Alexander Turikov (Russia). Version 0.1

Chess – Designer Evgeny Kornilov (Russia). Version 3

Woodpecker – Designer Evgeny Kornilov (Russia). Version 2

Gull – Developer Vadim Demishev (Russia). Version 1.2

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Download free Chess Engines – Komodo 11, Houdini

Chess – Wikipedia

This article is about the Western board game. For other chess games or other uses, see Chess (disambiguation).

Strategy board game

Chess is a two-player strategy board game played on a chessboard, a checkered gameboard with 64squares arranged in an 88 grid.[1] The game is played by millions of people worldwide. Chess is believed to be derived from the Indian game chaturanga some time before the 7thcentury. Chaturanga is also the likely ancestor of the Eastern strategy games xiangqi, janggi, and shogi. Chess reached Europe by the 9thcentury, due to the Umayyad conquest of Hispania. The pieces assumed their current powers in Spain in the late 15thcentury with the introduction of “Mad Queen Chess”; the modern rules were standardized in the 19thcentury.

Play does not involve hidden information. Each player begins with 16 pieces: one king, one queen, two rooks, two knights, two bishops, and eight pawns. Each of the six piece types moves differently, with the most powerful being the queen and the least powerful the pawn. The objective is to checkmate[note 1] the opponent’s king by placing it under an inescapable threat of capture. To this end, a player’s pieces are used to attack and capture the opponent’s pieces, while supporting each other. During the game, play typically involves making exchanges of one piece for an opponent’s similar piece, but also finding and engineering opportunities to trade advantageously, or to get a better position. In addition to checkmate, a player wins the game if the opponent resigns, or (in a timed game) runs out of time. There are also several ways that a game can end in a draw.

The first generally recognized World Chess Champion, Wilhelm Steinitz, claimed his title in 1886. Since 1948, the World Championship has been regulated by the Fdration Internationale des checs (FIDE), the game’s international governing body. FIDE also awards life-time master titles to skilled players, the highest of which is grandmaster. Many national chess organizations have a title system of their own. FIDE also organizes the Women’s World Championship, the World Junior Championship, the World Senior Championship, the Blitz and Rapid World Championships, and the Chess Olympiad, a popular competition among international teams. FIDE is a member of the International Olympic Committee, which can be considered as a recognition of chess as a sport.[2] Several national sporting bodies (for example the Spanish Consejo Superior de Deportes[3]) also recognize chess as a sport. Chess was included in the 2006 and 2010 Asian Games. There is also a Correspondence Chess World Championship and a World Computer Chess Championship. Online chess has opened amateur and professional competition to a wide and varied group of players.

Since the second half of the 20th century, chess engines (computers) have been programmed to play chess with increasing success, to the point where the strongest personal computers play at a higher level than the best human players. Since the 1990s, computer analysis has contributed significantly to chess theory, particularly in the endgame. The IBM computer Deep Blue was the first machine to overcome a reigning World Chess Champion in a match when it defeated Garry Kasparov in 1997. The rise of strong chess engines runnable on hand-held devices has led to increasing concerns about cheating during tournaments. There are many variants of chess that utilize different rules, pieces, or boards. One of these, Chess960, incorporates standard rules but employs 960 different possible starting positions, thus negating any advantage in opening preparation. Chess960 has gained widespread popularity as well as some FIDE recognition.

The rules of chess are published by FIDE (Fdration Internationale des checs), chess’s international governing body, in its Handbook.[4] Rules published by national governing bodies, or by unaffiliated chess organizations, commercial publishers, etc., may differ. FIDE’s rules were most recently revised in 2017.

Initial position, first row: rook, knight, bishop, queen, king, bishop, knight, and rook; second row: pawns

Chess is played on a square board of eight rows (called ranks, denoted 1 to 8) and eight columns (called files, denoted a to h). The 64 squares alternate in color and are referred to as light and dark squares. The chessboard is placed with a light square at the right-hand end of the rank nearest to each player.

By convention, the game pieces are divided into white and black sets, and the players are referred to as White and Black, respectively. Each player begins the game with 16 pieces of the specified color, consisting of one king, one queen, two rooks, two bishops, two knights, and eight pawns. The pieces are set out as shown in the diagram and photo, with each queen on a square of its own color (the white queen on a light square; the black queen on a dark square).

In competitive games, the colors are allocated by the organizers; in informal games, the colors are usually decided randomly, for example by concealing a white and black pawn in either hand and having the opponent choose, or by coin toss. The player with the white pieces moves first. After the first move, players alternate turns, moving one piece per turn (except for castling, when two pieces are moved). Pieces are moved to either an unoccupied square or one occupied by an opponent’s piece, which is captured and removed from play. With the sole exception of en passant, all pieces capture by moving to the square that the opponent’s piece occupies. A player may not make any move that would put or leave the player’s own king under attack. A player cannot “pass” a turn; one must make a legal move (this is the basis for the finesse called zugzwang).

If the player to move has no legal move, the game is over; the result is either checkmate (a loss for the player with no legal move) if the king is in check, or stalemate (a draw) if the king is not.

Each piece has its own way of moving. In the diagrams, the dots mark the squares to which the piece can move if there are no intervening piece(s) of either color (except the knight, which leaps over any intervening pieces).

Once in every game, each king can make a special move, known as castling. Castling consists of moving the king two squares along the first rank toward a rook (that is on the player’s first rank[note 2]) and then placing the rook on the last square that the king just crossed. Castling is permissible if the following conditions are met:[5]

When a pawn makes a two-step advance from its starting position and there is an opponent’s pawn on a square next to the destination square on an adjacent file, then the opponent’s pawn can capture it en passant (“in passing”), moving to the square the pawn passed over. This can only be done on the very next turn, otherwise the right to do so is forfeited. For example, in the animated diagram, the black pawn advances two steps from g7 to g5, and the white pawn on f5 can take it en passant on g6 (but only on White’s next move).

When a pawn advances to the eighth rank, as a part of the move it is promoted and must be exchanged for the player’s choice of queen, rook, bishop, or knight of the same color. Usually, the pawn is chosen to be promoted to a queen, but in some cases another piece is chosen; this is called underpromotion. In the animated diagram, the pawn on c7 can be advanced to the eighth rank and be promoted. There is no restriction placed on the piece promoted to, so it is possible to have more pieces of the same type than at the start of the game (e.g., two or more queens).

When a king is under immediate attack by one or two of the opponent’s pieces, it is said to be in check. A move in response to a check is legal only if it results in a position where the king is no longer in check. This can involve capturing the checking piece; interposing a piece between the checking piece and the king (which is possible only if the attacking piece is a queen, rook, or bishop and there is a square between it and the king); or moving the king to a square where it is not under attack. Castling is not a permissible response to a check.

The object of the game is to checkmate the opponent; this occurs when the opponent’s king is in check, and there is no legal way to remove it from attack. It is never legal for a player to make a move that puts or leaves the player’s own king in check. In casual games it is common to announce “check” when putting the opponent’s king in check, but this is not required by the rules of chess, and is not usually done in tournaments.

Games can be won in the following ways:

There are several ways games can end in a draw:

In competition, chess games are played with a time control. If a player’s time runs out before the game is completed, the game is automatically lost (provided the opponent has enough pieces left to deliver checkmate). The duration of a game ranges from long (or “classical”) games which can take up to seven hours (even longer if adjournments are permitted) to bullet chess (under 3minutes per player for the entire game). Intermediate between these are rapid chess games, lasting between 20minutes and two hours per game, a popular time control in amateur weekend tournaments.

Time is controlled using a chess clock that has two displays, one for each player’s remaining time. Analog chess clocks have been largely replaced by digital clocks, which allow for time controls with increments.

Time controls are also enforced in correspondence chess competition. A typical time control is 50 days for every 10 moves.

Chess is believed to have originated in Eastern India, c. 280550,[8] in the Gupta Empire,[9][10][11][12] where its early form in the 6thcentury was known as chaturaga (Sanskrit: ), literally four divisions [of the military] infantry, cavalry, elephants, and chariotry, represented by the pieces that would evolve into the modern pawn, knight, bishop, and rook, respectively. Thence it spread eastward and westward along the Silk Road. The earliest evidence of chess is found in the nearby Sassanid Persia around 600, where the game came to be known by the name chatrang. Chatrang was taken up by the Muslim world after the Islamic conquest of Persia (63344), where it was then named shatranj, with the pieces largely retaining their Persian names. In Spanish “shatranj” was rendered as ajedrez (“al-shatranj”), in Portuguese as xadrez, and in Greek as (zatrikion, which comes directly from the Persian chatrang),[13] but in the rest of Europe it was replaced by versions of the Persian shh (“king”), which was familiar as an exclamation and became the English words “check” and “chess”.[note 4]

The oldest archaeological chess artifacts, ivory pieces, were excavated in ancient Afrasiab, today’s Samarkand, in Uzbekistan, central Asia, and date to about 760, with some of them possibly older. The oldest known chess manual was in Arabic and dates to 840850, written by al-Adli ar-Rumi (800870), a renowned Arab chess player, titled Kitab ash-shatranj (Book of the chess). This is a lost manuscript, but referenced in later works. The eastern migration of chess, into China and Southeast Asia, has even less documentation than its migration west. The first reference to chess, called Xiang Qi, in China comes in the xun gua l (, record of the mysterious and strange) dating to about 800. Alternatively, some contend that chess arose from Chinese chess or one of its predecessors,[14] although this has been contested.[15]

The game reached Western Europe and Russia by at least three routes, the earliest being in the 9thcentury. By the year 1000, it had spread throughout Europe.[16] Introduced into the Iberian Peninsula by Muslims in the 10thcentury, it was described in a famous 13th-century manuscript covering shatranj, backgammon, and dice named the Libro de los juegos.

Around 1200, the rules of shatranj started to be modified in southern Europe, and around 1475, several major changes made the game essentially as it is known today.[16] These modern rules for the basic moves had been adopted in Italy and Spain.[17][18]Pawns gained the option of advancing two squares on their first move, while bishops and queens acquired their modern abilities. The queen replaced the earlier vizier chess piece towards the end of the 10thcentury and by the 15thcentury had become the most powerful piece;[19] consequently modern chess was referred to as “Queen’s Chess” or “Mad Queen Chess”.[20] Castling, derived from the “kings leap” usually in combination with a pawn or rook move to bring the king to safety, was introduced. These new rules quickly spread throughout western Europe.

Writings about the theory of how to play chess began to appear in the 15thcentury. The Repeticin de Amores y Arte de Ajedrez (Repetition of Love and the Art of Playing Chess) by Spanish churchman Luis Ramirez de Lucena was published in Salamanca in 1497.[18] Lucena and later masters like Portuguese Pedro Damiano, Italians Giovanni Leonardo Di Bona, Giulio Cesare Polerio and Gioachino Greco, and Spanish bishop Ruy Lpez de Segura developed elements of openings and started to analyze simple endgames.

In the 18th century, the center of European chess life moved from the Southern European countries to France. The two most important French masters were Franois-Andr Danican Philidor, a musician by profession, who discovered the importance of pawns for chess strategy, and later Louis-Charles Mah de La Bourdonnais, who won a famous series of matches with the Irish master Alexander McDonnell in 1834.[21] Centers of chess activity in this period were coffee houses in major European cities like Caf de la Rgence in Paris and Simpson’s Divan in London.[22][23]

The rules concerning stalemate were finalized in the early 19thcentury. Also in the 19thcentury, the convention that White moves first was established (formerly either White or Black could move first). Finally the rules around castling were standardized variations in the castling rules had persisted in Italy until the late 19thcentury. The resulting standard game is sometimes referred to as Western chess[24] or international chess,[25] particularly in Asia where other games of the chess family such as xiangqi are prevalent. Since the 19thcentury, the only rule changes have been technical in nature, for example establishing the correct procedure for claiming a draw by repetition.

As the 19th century progressed, chess organization developed quickly. Many chess clubs, chess books, and chess journals appeared. There were correspondence matches between cities; for example, the London Chess Club played against the Edinburgh Chess Club in 1824.[26] Chess problems became a regular part of 19th-century newspapers; Bernhard Horwitz, Josef Kling, and Samuel Loyd composed some of the most influential problems. In 1843, von der Lasa published his and Bilguer’s Handbuch des Schachspiels (Handbook of Chess), the first comprehensive manual of chess theory.

Chess was occasionally criticised in the 19th century as a waste of time.[27][28]

The first modern chess tournament was organized by Howard Staunton, a leading English chess player, and was held in London in 1851. It was won by the German Adolf Anderssen, who was hailed as the leading chess master. His brilliant, energetic attacking style was typical for the time.[29][30] Sparkling games like Anderssen’s Immortal Game and Evergreen Game or Morphy’s “Opera Game” were regarded as the highest possible summit of the chess art.[31]

The romantic era was characterized by opening gambits (sacrificing pawns or even pieces), daring attacks, and brazen sacrifices. Many elaborate and beautiful but unsound move sequences called “combinations” were played by the masters of the time. The game was played more for art than theory. A profound belief that chess merit resided in the players’ genius rather than inherent in the position on the board pervaded chess practice.

Deeper insight into the nature of chess came with the American Paul Morphy, an extraordinary chess prodigy. Morphy won against all important competitors (except Staunton, who refused to play), including Anderssen, during his short chess career between 1857 and 1863. Morphy’s success stemmed from a combination of brilliant attacks and sound strategy; he intuitively knew how to prepare attacks.[32]

Prague-born Wilhelm Steinitz beginning in 1873 described how to avoid weaknesses in one’s own position and how to create and exploit such weaknesses in the opponent’s position.[33] The scientific approach and positional understanding of Steinitz revolutionized the game. Steinitz was the first to break a position down into its components.[34] Before Steinitz, players brought their queen out early, did not completely develop their other pieces, and mounted a quick attack on the opposing king, which either succeeded or failed. The level of defense was poor and players did not form any deep plan.[35] In addition to his theoretical achievements, Steinitz founded an important tradition: his triumph over the leading German master Johannes Zukertort in 1886 is regarded as the first official World Chess Championship. Steinitz lost his crown in 1894 to a much younger player, the German mathematician Emanuel Lasker, who maintained this title for 27years, the longest tenure of all World Champions.[36]

After the end of the 19th century, the number of master tournaments and matches held annually quickly grew. Some sources state that in 1914 the title of chess Grandmaster was first formally conferred by Tsar Nicholas II of Russia to Lasker, Capablanca, Alekhine, Tarrasch, and Marshall, but this is a disputed claim.[note 5] The tradition of awarding such titles was continued by the World Chess Federation (FIDE), founded in 1924 in Paris. In 1927, the Women’s World Chess Championship was established; the first to hold the title was Czech-English master Vera Menchik.[37]

It took a prodigy from Cuba, Jos Ral Capablanca (World Champion 19211927), who loved simple positions and endgames, to end the German-speaking dominance in chess; he was undefeated in tournament play for eight years, until 1924. His successor was Russian-French Alexander Alekhine, a strong attacking player who died as the world champion in 1946. He briefly lost the title to Dutch player Max Euwe in 1935 and regained it two years later.[38]

Between the world wars, chess was revolutionized by the new theoretical school of so-called hypermodernists like Aron Nimzowitsch and Richard Rti. They advocated controlling the center of the board with distant pieces rather than with pawns, thus inviting opponents to occupy the center with pawns, which become objects of attack.[39]

After the death of Alekhine, a new World Champion was sought. FIDE, which has controlled the title since then (except for one interruption), ran a tournament of elite players. The winner of the 1948 tournament, Russian Mikhail Botvinnik, started an era of Soviet dominance in the chess world. Until the end of the Soviet Union, there was only one non-Soviet champion, American Bobby Fischer (champion 19721975).[40] Botvinnik revolutionized opening theory. Previously Black strove for equality, to neutralize White’s first-move advantage. As Black, Botvinnik strove for the initiative from the beginning.[41] In the previous informal system of World Championships, the current champion decided which challenger he would play for the title and the challenger was forced to seek sponsors for the match. FIDE set up a new system of qualifying tournaments and matches. The world’s strongest players were seeded into Interzonal tournaments, where they were joined by players who had qualified from Zonal tournaments. The leading finishers in these Interzonals would go on the “Candidates” stage, which was initially a tournament, and later a series of knockout matches. The winner of the Candidates would then play the reigning champion for the title. A champion defeated in a match had a right to play a rematch a year later. This system operated on a three-year cycle. Botvinnik participated in championship matches over a period of fifteen years. He won the world championship tournament in 1948 and retained the title in tied matches in 1951 and 1954. In 1957, he lost to Vasily Smyslov, but regained the title in a rematch in 1958. In 1960, he lost the title to the 23-year-old Latvian prodigy Mikhail Tal, an accomplished tactician and attacking player. Botvinnik again regained the title in a rematch in 1961.

Following the 1961 event, FIDE abolished the automatic right of a deposed champion to a rematch, and the next champion, Armenian Tigran Petrosian, a player renowned for his defensive and positional skills, held the title for two cycles, 19631969. His successor, Boris Spassky from Russia (champion 19691972), won games in both positional and sharp tactical style.[42] The next championship, the so-called Match of the Century, saw the first non-Soviet challenger since World War II, American Bobby Fischer, who defeated his Candidates opponents by unheard-of margins and clearly won the world championship match. In 1975, however, Fischer refused to defend his title against Soviet Anatoly Karpov when FIDE did not meet his demands, and Karpov obtained the title by default.[43] Fischer modernized many aspects of chess, especially by extensively preparing openings.[44]

Karpov defended his title twice against Viktor Korchnoi and dominated the 1970s and early 1980s with a string of tournament successes.[45] Karpov’s reign finally ended in 1985 at the hands of Garry Kasparov, another Soviet player from Baku, Azerbaijan. Kasparov and Karpov contested five world title matches between 1984 and 1990; Karpov never won his title back.[46] In 1993, Garry Kasparov and Nigel Short broke with FIDE to organize their own match for the title and formed a competing Professional Chess Association (PCA). From then until 2006, there were two simultaneous World Champions and World Championships: the PCA or Classical champion extending the Steinitzian tradition in which the current champion plays a challenger in a series of many games, and the other following FIDE’s new format of many players competing in a tournament to determine the champion. Kasparov lost his Classical title in 2000 to Vladimir Kramnik of Russia.[47] The World Chess Championship 2006, in which Kramnik beat the FIDE World Champion Veselin Topalov, reunified the titles and made Kramnik the undisputed World Chess Champion.[48] In September 2007, he lost the title to Viswanathan Anand of India, who won the championship tournament in Mexico City. Anand defended his title in the revenge match of 2008,[49] 2010 and 2012. In 2013, Magnus Carlsen beat Anand in the 2013 World Chess Championship.[50] He defended his title the following year, again against Anand. Carlsen confirmed his title in 2016 against the Russian Sergey Karjakin [51] and in 2018 against the American Fabiano Caruana [52], in both occasions by a rapid tiebreaker match after equality in 12 games of classical time control, and is the reigning world champion.

In the Middle Ages and during the Renaissance, chess was a part of noble culture; it was used to teach war strategy and was dubbed the “King’s Game”.[53] Gentlemen are “to be meanly seene in the play at Chestes”, says the overview at the beginning of Baldassare Castiglione’s The Book of the Courtier (1528, English 1561 by Sir Thomas Hoby), but chess should not be a gentleman’s main passion. Castiglione explains it further:

And what say you to the game at chestes? It is truely an honest kynde of enterteynmente and wittie, quoth Syr Friderick. But me think it hath a fault, whiche is, that a man may be to couning at it, for who ever will be excellent in the playe of chestes, I beleave he must beestowe much tyme about it, and applie it with so much study, that a man may assoone learne some noble scyence, or compase any other matter of importaunce, and yet in the ende in beestowing all that laboure, he knoweth no more but a game. Therfore in this I beleave there happeneth a very rare thing, namely, that the meane is more commendable, then the excellency.[54]

Many of the elaborate chess sets used by the aristocracy have been lost, but others partially survive, such as the Lewis chessmen.

Chess was often used as a basis of sermons on morality. An example is Liber de moribus hominum et officiis nobilium sive super ludo scacchorum (‘Book of the customs of men and the duties of nobles or the Book of Chess’), written by an Italian Dominican monk Jacobus de Cessolis c.1300. This book was one of the most popular of the Middle Ages.[55] The work was translated into many other languages (the first printed edition was published at Utrecht in 1473) and was the basis for William Caxton’s The Game and Playe of the Chesse (1474), one of the first books printed in English.[56] Different chess pieces were used as metaphors for different classes of people, and human duties were derived from the rules of the game or from visual properties of the chess pieces:[57]

The knyght ought to be made alle armed upon an hors in suche wyse that he haue an helme on his heed and a spere in his ryght hande/ and coueryd wyth his sheld/ a swerde and a mace on his lyft syde/ Cladd wyth an hawberk and plates to fore his breste/ legge harnoys on his legges/ Spores on his heelis on his handes his gauntelettes/ his hors well broken and taught and apte to bataylle and couerid with his armes/ whan the knyghtes ben maad they ben bayned or bathed/ that is the signe that they shold lede a newe lyf and newe maners/ also they wake alle the nyght in prayers and orysons vnto god that he wylle gyue hem grace that they may gete that thynge that they may not gete by nature/ The kynge or prynce gyrdeth a boute them a swerde in signe/ that they shold abyde and kepe hym of whom they take theyr dispenses and dignyte.[58]

Known in the circles of clerics, students, and merchants, chess entered into the popular culture of Middle Ages. An example is the 209th song of Carmina Burana from the 13thcentury, which starts with the names of chess pieces, Roch, pedites, regina…[59]

During the Age of Enlightenment, chess was viewed as a means of self-improvement. Benjamin Franklin, in his article “The Morals of Chess” (1750), wrote:

The Game of Chess is not merely an idle amusement; several very valuable qualities of the mind, useful in the course of human life, are to be acquired and strengthened by it, so as to become habits ready on all occasions; for life is a kind of Chess, in which we have often points to gain, and competitors or adversaries to contend with, and in which there is a vast variety of good and ill events, that are, in some degree, the effect of prudence, or the want of it. By playing at Chess then, we may learn:

I. Foresight, which looks a little into futurity, and considers the consequences that may attend an action […]

II. Circumspection, which surveys the whole Chess-board, or scene of action: the relation of the several Pieces, and their situations […]

III. Caution, not to make our moves too hastily […][60]

With these or similar views, chess is taught to children in schools around the world today. Many schools host chess clubs, and there are many scholastic tournaments specifically for children. Tournaments are held regularly in many countries, hosted by organizations such as the United States Chess Federation and the National Scholastic Chess Foundation.[61]

Chess is often depicted in the arts; significant works where chess plays a key role range from Thomas Middleton’s A Game at Chess to Through the Looking-Glass by Lewis Carroll, to Vladimir Nabokov’s The Defense, to The Royal Game by Stefan Zweig. Chess is featured in films like Ingmar Bergman’s The Seventh Seal and Satyajit Ray’s The Chess Players.

Chess is also present in contemporary popular culture. For example, the characters in Star Trek play a futuristic version of the game called “Tri-Dimensional Chess”. “Wizard’s Chess” is featured in J.K. Rowling’s Harry Potter plays. The hero of Searching for Bobby Fischer struggles against adopting the aggressive and misanthropic views of a world chess champion.[62] Chess is used as the core theme in the musical Chess by Tim Rice, Bjrn Ulvaeus, and Benny Andersson. The thriller film Knight Moves is about a chess grandmaster who is accused of being a serial killer. Pawn Sacrifice, starring Tobey Maguire as Bobby Fischer and Liev Schreiber as Boris Spassky, depicts the drama surrounding the 1972 World Chess Championship in Iceland during the Cold War.[63]

In 2016 in Saudi Arabia, Grand Mufti Abdul-Aziz ibn Abdullah Al ash-Sheikh issued a religious fatwa ruling that chess is forbidden in Islam because it constitutes gambling. Stating “chess is a waste of time and an opportunity to squander money. It causes enmity and hatred between people.” However, this fatwa is not legally binding and chess remains a popular game in Muslim countries.[64]

Chess games and positions are recorded using a system of notation, most commonly algebraic chess notation.[65] Abbreviated algebraic (or short algebraic) notation generally records moves in the format:

The pieces are identified by their initials. In English, these are K (king), Q (queen), R (rook), B (bishop), and N (knight; N is used to avoid confusion with king). For example, Qg5 means “queen moves to the g-file, 5th rank” (that is, to the square g5). Chess literature published in other languages may use different initials for pieces, or figurine algebraic notation (FAN) may be used to avoid language issues. To resolve ambiguities, an additional letter or number is added to indicate the file or rank from which the piece moved (e.g. Ngf3 means “knight from the g-file moves to the square f3”; R1e2 means “rook on the first rank moves to e2”). The letter P for pawn is not used; so e4 means “pawn moves to the square e4”.

If the piece makes a capture, “x” is inserted before the destination square. Thus Bxf3 means “bishop captures on f3”. When a pawn makes a capture, the file from which the pawn departed is used in place of a piece initial, and ranks may be omitted if unambiguous. For example, exd5 (pawn on the e-file captures the piece on d5) or exd (pawn on the e-file captures a piece somewhere on the d-file). Particularly in Germany, some publications use “:” rather than “x” to indicate capture, but this is now rare. Some publications omit the capture symbol altogether; so exd5 would be rendered simply as ed.

If a pawn moves to its last rank, achieving promotion, the piece chosen is indicated after the move (for example, e1Q or e1=Q). Castling is indicated by the special notations 0-0 for kingside castling and 0-0-0 for queenside castling. An en passant capture is sometimes marked with the notation “e.p.” A move that places the opponent’s king in check usually has the notation “+” added (the notation “++” for a double check is considered obsolete). Checkmate can be indicated by “#”. At the end of the game, “10” means White won, “01” means Black won, and “” indicates a draw.[66]

Chess moves can be annotated with punctuation marks and other symbols. (For example: “!” indicates a good move; “!!” an excellent move; “?” a mistake; “??” a blunder; “!?” an interesting move that may not be best; or “?!” a dubious move not easily refuted.[67])

For example, one variation of a simple trap known as the Scholar’s mate (see animated diagram) can be recorded:

The text-based Portable Game Notation (PGN), which is understood by chess software, is based on short form English language algebraic notation.

Until about 1980, the majority of English language chess publications used a form of descriptive notation. In descriptive notation, files are named according to the piece which occupies the back rank at the start of the game, and each square has two different names depending on whether it is from White’s or Black’s point of view. For example, the square known as “e3” in algebraic notation is “K3” (King’s 3rd) from White’s point of view, and “K6” (King’s 6th) from Black’s point of view. When recording captures, the captured piece is named rather than the square on which it is captured (except to resolve ambiguities). Thus, Scholar’s mate is rendered in descriptive notation:

A few players still prefer descriptive notation, but it is no longer recognized by FIDE.

Another system is ICCF numeric notation, recognized by the International Correspondence Chess Federation though its use is in decline. Squares are identified by numeric coordinates, for example a1 is “11” and h8 is “88”. Moves are described by the “from” and “to” squares, and captures are not indicated. For example, the opening move 1.e4 is rendered as 1.5254. Castling is described by the king’s move only, for example 5171 for White castling kingside, 5838 for Black castling queenside.

A chess opening is the group of initial moves of a game (the “opening moves”). Recognized sequences of opening moves are referred to as openings and have been given names such as the Ruy Lopez or Sicilian Defense. They are catalogued in reference works such as the Encyclopaedia of Chess Openings. There are dozens of different openings, varying widely in character from quiet positional play (for example, the Rti Opening) to very aggressive (the Latvian Gambit). In some opening lines, the exact sequence considered best for both sides has been worked out to more than 30 moves.[68] Professional players spend years studying openings and continue doing so throughout their careers, as opening theory continues to evolve.

The fundamental strategic aims of most openings are similar:[69]

Most players and theoreticians consider that White, by virtue of the first move, begins the game with a small advantage. This initially gives White the initiative.[70] Black usually strives to neutralize White’s advantage and achieve equality, or to develop dynamic counterplay in an unbalanced position.

The middlegame is the part of the game which starts after the opening. There is no clear line between the opening and the middlegame, but typically the middlegame will start when most pieces have been developed. (Similarly, there is no clear transition from the middlegame to the endgame; see start of the endgame.) Because the opening theory has ended, players have to form plans based on the features of the position, and at the same time take into account the tactical possibilities of the position.[71] The middlegame is the phase in which most combinations occur. Combinations are a series of tactical moves executed to achieve some gain. Middlegame combinations are often connected with an attack against the opponent’s king. Some typical patterns have their own names; for example, the Boden’s Mate or the LaskerBauer combination.[72]

Specific plans or strategic themes will often arise from particular groups of openings which result in a specific type of pawn structure. An example is the minority attack, which is the attack of queenside pawns against an opponent who has more pawns on the queenside. The study of openings is therefore connected to the preparation of plans that are typical of the resulting middlegames.[73]

Another important strategic question in the middlegame is whether and how to reduce material and transition into an endgame (i.e. simplify). Minor material advantages can generally be transformed into victory only in an endgame, and therefore the stronger side must choose an appropriate way to achieve an ending. Not every reduction of material is good for this purpose; for example, if one side keeps a light-squared bishop and the opponent has a dark-squared one, the transformation into a bishops and pawns ending is usually advantageous for the weaker side only, because an endgame with bishops on opposite colors is likely to be a draw, even with an advantage of a pawn, or sometimes even with a two-pawn advantage.[74]

The side having to move is disadvantaged.

The endgame (also end game or ending) is the stage of the game when there are few pieces left on the board. There are three main strategic differences between earlier stages of the game and the endgame:[75]

Endgames can be classified according to the type of pieces remaining on the board. Basic checkmates are positions in which one side has only a king and the other side has one or two pieces and can checkmate the opposing king, with the pieces working together with their king. For example, king and pawn endgames involve only kings and pawns on one or both sides, and the task of the stronger side is to promote one of the pawns. Other more complicated endings are classified according to pieces on the board other than kings, such as “rook and pawn versus rook” endgames.

Chess strategy consists of setting and achieving long-term positioning advantages during the game for example, where to place different pieces while tactics concentrate on immediate maneuver. These two parts of the chess-playing process cannot be completely separated, because strategic goals are mostly achieved through tactics, while the tactical opportunities are based on the previous strategy of play. A game of chess is normally divided into three phases: opening, typically the first 10 moves, when players move their pieces to useful positions for the coming battle; then middlegame; and last the endgame, when most of the pieces are gone, kings typically take a more active part in the struggle, and pawn promotion is often decisive.

23.Bh5+ and now:

In chess, tactics in general concentrate on short-term actions so short-term that they can be calculated in advance by a human player or by a computer. The possible depth of calculation depends on the player’s ability. In quiet positions with many possibilities on both sides, a deep calculation is more difficult and may not be practical, while in “tactical” positions with a limited number of forced variations, strong players can calculate long sequences of moves.

Simple one-move or two-move tactical actions threats, exchanges of material, and double attacks can be combined into more complicated combinations, sequences of tactical maneuvers that are often forced from the point of view of one or both players.[77] Theoreticians describe many elementary tactical methods and typical maneuvers; for example, pins, forks, skewers, batteries, discovered attacks (especially discovered checks), zwischenzugs, deflections, decoys, sacrifices, underminings, overloadings, and interferences.[78]

A forced variation that involves a sacrifice and usually results in a tangible gain is called a combination.[77] Brilliant combinations such as those in the Immortal Game are considered beautiful and are admired by chess lovers. A common type of chess exercise, aimed at developing players’ skills, is a position where a decisive combination is available and challenging them to find it.[79]

Chess strategy is concerned with evaluation of chess positions and with setting up goals and long-term plans for the future play. During the evaluation, players must take into account numerous factors such as the value of the pieces on the board, control of the center and centralization, the pawn structure, king safety, and the control of key squares or groups of squares (for example, diagonals, open files, and dark or light squares).

The most basic step in evaluating a position is to count the total value of pieces of both sides.[80] The point values used for this purpose are based on experience; usually pawns are considered worth one point, knights and bishops about three points each, rooks about five points (the value difference between a rook and a bishop or knight being known as the exchange), and queens about nine points. The king is more valuable than all of the other pieces combined, since its checkmate loses the game. But in practical terms, in the endgame the king as a fighting piece is generally more powerful than a bishop or knight but less powerful than a rook.[81] These basic values are then modified by other factors like position of the piece (e.g. advanced pawns are usually more valuable than those on their initial squares), coordination between pieces (e.g. a pair of bishops usually coordinate better than a bishop and a knight), or the type of position (e.g. knights are generally better in closed positions with many pawns while bishops are more powerful in open positions).[82]

…and its pawn “Rauzer formation”

Another important factor in the evaluation of chess positions is the pawn structure (sometimes known as the pawn skeleton): the configuration of pawns on the chessboard.[84] Since pawns are the least mobile of the pieces, the pawn structure is relatively static and largely determines the strategic nature of the position. Weaknesses in the pawn structure, such as isolated, doubled, or backward pawns and holes, once created, are often permanent. Care must therefore be taken to avoid these weaknesses unless they are compensated by another valuable asset (for example, by the possibility of developing an attack).[85]

Contemporary chess is an organized sport with structured international and national leagues, tournaments, and congresses. Chess’s international governing body is FIDE (Fdration Internationale des checs). Most countries have a national chess organization as well (such as the US Chess Federation and English Chess Federation) which in turn is a member of FIDE. FIDE is a member of the International Olympic Committee,[86] but the game of chess has never been part of the Olympic Games; chess does have its own Olympiad, held every two years as a team event.

The current World Chess Champion is Magnus Carlsen of Norway.[87] The reigning Women’s World Champion is Hou Yifan from China.[88] The world’s highest rated female player, Judit Polgr, has never participated in the Women’s World Chess Championship, instead preferring to compete with the leading men and maintaining a ranking among the top male players.[89]

Other competitions for individuals include the World Junior Chess Championship, the European Individual Chess Championship, and the National Chess Championships. Invitation-only tournaments regularly attract the world’s strongest players. Examples include Spain’s Linares event, Monte Carlo’s Melody Amber tournament, the Dortmund Sparkassen meeting, Sofia’s M-tel Masters, and Wijk aan Zee’s Tata Steel tournament.

Regular team chess events include the Chess Olympiad and the European Team Chess Championship. The World Chess Solving Championship and World Correspondence Chess Championships include both team and individual events.

Besides these prestigious competitions, there are thousands of other chess tournaments, matches, and festivals held around the world every year catering to players of all levels. Chess is promoted as a “mind sport” by the Mind Sports Organisation, alongside other mental-skill games such as Contract Bridge, Go, and Scrabble.

The best players can be awarded specific lifetime titles by the world chess organization FIDE:[90]

All the titles are open to men and women. Separate women-only titles, such as Woman Grandmaster (WGM), are available. Beginning with Nona Gaprindashvili in 1978, a number of women have earned the GM title, and most of the top ten women in 2006 hold the unrestricted GM title.[note 6]

As of 2018[update], there are 1725 active grandmasters and 3903 international masters in the world. The top three countries with the largest numbers of grandmasters are Russia, the United States, and Germany, with 251, 98, and 96, respectively.[91]

International titles are awarded to composers and solvers of chess problems and to correspondence chess players (by the International Correspondence Chess Federation). National chess organizations may also award titles, usually to the advanced players still under the level needed for international titles; an example is the chess expert title used in the United States.

In order to rank players, FIDE, ICCF, and national chess organizations use the Elo rating system developed by Arpad Elo. Elo is a statistical system based on the assumption that the chess performance of each player in his or her games is a random variable. Arpad Elo thought of a player’s true skill as the average of that player’s performance random variable, and showed how to estimate the average from results of player’s games. The US Chess Federation implemented Elo’s suggestions in 1960, and the system quickly gained recognition as being both fairer and more accurate than older systems; it was adopted by FIDE in 1970.[note 7] A beginner or casual player typically has an Elo rating of less than 1000; an ordinary club player has a rating of about 1500, a strong club player about 2000, a grandmaster usually has a rating of over 2500, and an elite player has a rating of over 2700. The highest FIDE rating of all time, 2881, was achieved by Magnus Carlsen on the March 2014 FIDE rating list.[92]

Chess composition is the art of creating chess problems (also called chess compositions). The creator is known as a chess composer.[93] There are many types of chess problems; the two most important are:

Chess composition is a distinct branch of chess sport, and tournaments exist for both the composition and solving of chess problems.[96]

This is one of the most famous chess studies; it was published by Richard Rti 4 December 1921. It seems impossible to catch the advanced black pawn, while the black king can easily stop the white pawn. The solution is a diagonal advance, which brings the king to both pawns simultaneously:

Or 2…h3 3.Ke7 and the white king can support its pawn.

Now the white king comes just in time to support his pawn, or catch the black one.

Here is the original post:

Chess – Wikipedia