Solving chess consists of finding an optimal strategy for the game of chess ; that is, one by which one of the players ( White or Black ) can always force a victory, or either can force a draw (see solved game ). It is also related to more generally solving chess-like games (i.e. combinatorial games of perfect information ) such as Capablanca chess and infinite chess . In a weaker sense, solving chess may refer to proving which one of the three possible outcomes (White wins; Black wins; draw) is the result of two perfect players, without necessarily revealing the optimal strategy itself (see indirect proof ).
53-602: The Balogh Defense (also known as the Balogh Counter Gambit ) is an unusual chess opening beginning with the moves: It may also arise by transposition from the Staunton Gambit against the Dutch Defense , 1.d4 f5 2.e4!?, if Black declines the gambit with 2...d6. The defense is named for János Balogh (1892–1980), who was a Hungarian International Master of correspondence chess , and
106-437: A "dictionary" denoting an optimal move for each of the approximately 10 possible board positions (currently known to be about 5x10 ). The number of mathematical operations required to solve chess, however, may be significantly different than the number of operations required to produce the entire game-tree of chess. In particular, if White has a forced win, only a subset of the game-tree would require evaluation to confirm that
159-408: A dark square. This may be remembered by the phrases "light on the right" and "queen on her own color". In formal competition, the piece colors for every matchup are allocated to players by the organizers. In informal games, colors are decided either by mutual agreement, or randomly, for example by a coin toss, or by one player concealing a white pawn in one hand and a black pawn in the other and having
212-492: A forced-win exists (i.e. with no refutations from Black). Furthermore, Shannon's calculation for the complexity of chess assumes an average game length of 40 moves, but there is no mathematical basis to say that a forced win by either side would have any relation to this game length. Indeed, some expertly played games (grandmaster-level play) have been as short as 16 moves. For these reasons, mathematicians and game theorists have been reluctant to categorically state that solving chess
265-473: A practical time frame would therefore seem beyond any conceivable technology. Hans-Joachim Bremermann , a professor of mathematics and biophysics at the University of California at Berkeley , further argued in a 1965 paper that the "speed, memory, and processing capacity of any possible future computer equipment are limited by specific physical barriers: the light barrier , the quantum barrier , and
318-680: A role it assumed in 1948. The current World Champion is Ding Liren of China. The reigning Women's World Champion is Ju Wenjun from China. Other competitions for individuals include the World Junior Chess Championship , the European Individual Chess Championship , the tournaments for the World Championship qualification cycle , and the various national championships . Invitation-only tournaments regularly attract
371-511: A series of games between two players, or a team competition in which each player of one team plays one game against a player of the other team. Chess's international governing body is usually known by its French acronym FIDE (pronounced FEE-day) ( French : Fédération internationale des échecs), or International Chess Federation. FIDE's membership consists of the national chess organizations of over 180 countries; there are also several associate members, including various supra-national organizations,
424-510: A simple trap known as the Scholar's mate (see animated diagram) can be recorded: Variants of algebraic notation include long algebraic , in which both the departure and destination square are indicated; abbreviated algebraic , in which capture signs, check signs, and ranks of pawn captures may be omitted; and Figurine Algebraic Notation, used in chess publications for universal readability regardless of language. Portable Game Notation (PGN)
477-409: A strong master at over-the-board chess. The opening is rarely seen today because it weakens Black's kingside somewhat and often results in a backward e-pawn and/or a hole on e6 after Black's light-square bishop is exchanged . International Correspondence Chess Master Keith Hayward has recently written a series of articles arguing that the defense, though risky, is playable. Chess Chess
530-476: A wide variety of styles. The Staunton pattern is the most common, and is usually required for competition. Chess pieces are divided into two sets, usually light and dark colored, referred to as white and black , regardless of the actual color or design. The players of the sets are referred to as White and Black , respectively. Each set consists of sixteen pieces: one king , one queen , two rooks , two bishops , two knights , and eight pawns . The game
583-644: Is a board game for two players. It is sometimes called international chess or Western chess to distinguish it from related games such as xiangqi (Chinese chess) and shogi (Japanese chess). Chess is an abstract strategy game that involves no hidden information and no elements of chance . It is played on a chessboard with 64 squares arranged in an 8×8 grid. The players, referred to generically as "White" and "Black" , each control sixteen pieces : one king , one queen , two rooks , two bishops , two knights , and eight pawns . White moves first, followed by Black; then moves alternate. The object of
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#1732793984486636-399: Is a text-based file format for recording chess games, based on short form English algebraic notation with a small amount of markup . PGN files (suffix .pgn) can be processed by most chess software, as well as being easily readable by humans. Until about 1980, the majority of English language chess publications used descriptive notation , in which files are identified by the initial letter of
689-473: Is an intractable problem. In 1950, Shannon calculated, based on a game tree complexity of 10 and a computer operating at one megahertz (a big stretch at that time: the UNIVAC 1 introduced in 1951 could perform ~2000 operations per second or 2 kilohertz) that could evaluate a terminal node in 1 microsecond would take 10 years to make its first move. Even allowing for technological advances, solving chess within
742-415: Is compulsory; a player may not skip a turn, even when having to move is detrimental . Each piece has its own way of moving. In the diagrams, crosses 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). All pieces except the pawn can capture an enemy piece if it is on a square to which they could move if
795-423: 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 competitions. A typical time control is 50 days for every 10 moves. Historically, many different notation systems have been used to record chess moves;
848-409: Is increased, such as in large chess variants, and infinite chess . Information theorist Claude Shannon in 1950 outlined a theoretical procedure for playing a perfect game (i.e. solving chess): "With chess it is possible, in principle, to play a perfect game or construct a machine to do so as follows: One considers in a given position all possible moves, then all moves for the opponent, etc., to
901-399: 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 get it out of check. 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
954-467: Is not guaranteed that this is the absolute limit for the eight-piece tablebase. A variant first described by Claude Shannon provides an argument about the game-theoretic value of chess: he proposes allowing the move of “pass”. In this variant, it is provable with a strategy stealing argument that the first player has at least a draw thus: if the first player has a winning move in the initial position, let him play it, else pass. The second player now faces
1007-411: Is not required by the rules of chess and is usually not done in tournaments. Once per game, each king can make a move known as castling . Castling consists of moving the king two squares toward a rook of the same color on the same rank, and then placing the rook on the square that the king crossed. Castling is permissible if the following conditions are met: Castling is still permitted if
1060-422: Is played on a square board of eight rows (called ranks ) and eight columns (called files ). Although it does not affect game play, by convention the 64 squares alternate in color and are referred to as light and dark squares. Common colors for wooden chessboards are light and dark brown, while vinyl chessboards are commonly buff and green. To start the game, White's pieces are placed on
1113-491: Is recognized in FIDE-sanctioned events; game scores recorded in a different notation system may not be used as evidence in the event of a dispute. Chess is often played casually in public spaces such as parks and town squares. Contemporary chess is an organized sport with structured international and national leagues, tournaments, and congresses . Thousands of chess tournaments, matches, and festivals are held around
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#17327939844861166-436: Is the current World Champion. A huge body of chess theory has developed since the game's inception. Aspects of art are found in chess composition , and chess in its turn influenced Western culture and the arts , and has connections with other fields such as mathematics , computer science , and psychology . One of the goals of early computer scientists was to create a chess-playing machine . In 1997, Deep Blue became
1219-526: Is usually calculated as 1 point for each game won and one-half point for each game drawn. Variations such as "football scoring" (3 points for a win, 1 point for a draw) may be used by tournament organizers, but ratings are always calculated on the basis of standard scoring. A player's score may be reported as total score out of games played (e.g. 5½/8), points for versus points against (e.g. 5½–2½), or by number of wins, losses and draws (e.g. +4−1=3). The term "match" refers not to an individual game, but to either
1272-885: The International Braille Chess Association (IBCA), International Committee of Chess for the Deaf (ICCD), and the International Physically Disabled Chess Association (IPCA). FIDE is recognized as a sports governing body by the International Olympic Committee , but chess has never been part of the Olympic Games . FIDE's most visible activity is organizing the World Chess Championship ,
1325-431: The thermodynamical barrier . These limitations imply, for example, that no computer, however constructed, will ever be able to examine the entire tree of possible move sequences of the game of chess." Nonetheless, Bremermann did not foreclose the possibility that a computer would someday be able to solve chess. He wrote, "In order to have a computer play a perfect or nearly perfect game, it will be necessary either to analyze
1378-463: The Sepoys can be easily memorised. The 5×5 Gardner's Minichess variant has been weakly solved as a draw. Although losing chess is played on an 8×8 board, its forced capture rule greatly limits its complexity, and a computational analysis managed to weakly solve this variant as a win for White. The prospect of solving individual, specific, chess-like games becomes more difficult as the board-size
1431-418: The computational effort that might be required to solve the game. Endgame tablebases are computerized databases that contain precalculated exhaustive analyses of positions with small numbers of pieces remaining on the board. Tablebases have solved chess to a limited degree, determining perfect play in a number of endgames , including all non-trivial endgames with no more than seven pieces or pawns (including
1484-584: The end of the 15th century, with standardization and universal acceptance by the end of the 19th century. Today, chess is one of the world's most popular games, with millions of players worldwide. Organized chess arose in the 19th century. Chess competition today is governed internationally by FIDE ( Fédération Internationale des Échecs ; the International Chess Federation). The first universally recognized World Chess Champion , Wilhelm Steinitz , claimed his title in 1886; Ding Liren
1537-479: The end of the game (in each variation). The end must occur, by the rules of the games after a finite number of moves (remembering the 50 move drawing rule ). Each of these variations ends in win, loss or draw. By working backward from the end one can determine whether there is a forced win, the position is a draw or is lost." Shannon then went on to estimate that solving chess according to that procedure would require comparing some 10 possible game variations, or having
1590-404: The end of the game, " 1–0 " means White won, " 0–1 " means Black won, and " ½–½ " indicates a draw. 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. For example, one variation of
1643-448: The enemy pawn's two-square advance; otherwise, the right to do so is forfeited. For example, in the animated diagram, the black pawn advances two squares from g7 to g5, and the white pawn on f5 can take it en passant on g6 (but only immediately after the black pawn's advance). When a pawn advances to its eighth rank , as part of the move, it is promoted and must be exchanged for the player's choice of queen, rook, bishop, or knight of
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1696-664: The first computer to beat a reigning World Champion in a match when it defeated Garry Kasparov . Today's chess engines are significantly stronger than the best human players and have deeply influenced the development of chess theory; however, chess is not a solved game . The rules of chess are published by FIDE (Fédération Internationale des Échecs; "International Chess Federation"), chess's world governing body, in its Handbook . Rules published by national governing bodies , or by unaffiliated chess organizations, commercial publishers, etc., may differ in some details. FIDE's rules were most recently revised in 2023. Chess sets come in
1749-423: The first rank in the following order, from left to right: rook, knight, bishop, queen, king, bishop, knight, rook. Pawns are placed on each square of the second rank. Black's position mirrors White's, with equivalent pieces on every file. The board is oriented so that the right-hand corner nearest each player is a light square; as a result the white queen always starts on a light square, while the black queen starts on
1802-407: The first rank moves to e2"). For pawns, no letter initial is used; so e4 means "pawn moves to the square e4". If the piece makes a capture, "x" is usually 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 to identify the pawn making the capture, for example, exd5 (pawn on the e-file captures
1855-436: The g-file, 5th rank" (that is, to the square g5). Different initials may be used for other languages. In chess literature, figurine algebraic notation (FAN) is frequently used to aid understanding independent of language. 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
1908-454: The game completely ... or to analyze the game in an approximate way and combine this with a limited amount of tree searching. ... A theoretical understanding of such heuristic programming, however, is still very much wanting." Recent scientific advances have not significantly changed these assessments. The game of checkers was (weakly) solved in 2007, but it has roughly the square root of the number of positions in chess. Jonathan Schaeffer ,
1961-567: The game is to checkmate (threaten with inescapable capture) the enemy king. There are also several ways a game can end in a draw . The recorded history of chess goes back at least to the emergence of a similar game, chaturanga , in seventh-century India . After its introduction in Persia , it spread to the Arab world and then to Europe. The rules of chess as they are known today emerged in Europe at
2014-414: The opponent choose. White moves first, after which players alternate turns, moving one piece per turn (except for castling , when two pieces are moved). A piece is 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. Moving
2067-442: 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 3 minutes per player for the entire game). Intermediate between these are rapid chess games, lasting between one and two hours per game, a popular time control in amateur weekend tournaments. Time
2120-427: The piece chosen is indicated after the move (for example, e1=Q or e1Q ). Castling is indicated by the special notations 0-0 (or O-O ) for kingside castling and 0-0-0 (or O-O-O ) for queenside castling. A move that places the opponent's king in check usually has the notation " + " added. There are no specific notations for discovered check or double check . Checkmate can be indicated by " # ". At
2173-443: The piece on d5). Ranks may be omitted if unambiguous, for example, exd (pawn on the e-file captures a piece somewhere on the d-file). A minority of publications use " : " to indicate a capture, and some omit the capture symbol altogether. In its most abbreviated form, exd5 may be rendered simply as ed . An en passant capture may optionally be marked with the notation " e.p. " If a pawn moves to its last rank, achieving promotion,
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2226-555: The piece that occupies the first rank at the beginning of the game. In descriptive notation, the common opening move 1.e4 is rendered as "1.P-K4" ("pawn to king four"). Another system is ICCF numeric notation , recognized by the International Correspondence Chess Federation though its use is in decline. In tournament games, players are normally required to keep a score (record of the game). For this purpose, only algebraic notation
2279-429: The required piece is not available (e.g. a second queen) an inverted rook is sometimes used as a substitute, but this is not recognized in FIDE-sanctioned games. A game can be won in the following ways: There are several ways a game 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
2332-402: The rook is under attack, or if the rook crosses an attacked square. 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 be done only on the turn immediately following
2385-407: 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 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). If
2438-495: The same situation owing to the mirror symmetry of the initial position: if the first player had no winning move in the first instance, the second player has none now. Therefore, the second player can at best draw, and the first player can at least draw, so a perfect game results in the first player winning or drawing. Some chess variants which are simpler than chess have been solved. A winning strategy for Black in Maharajah and
2491-415: The square were unoccupied. Pieces are generally not permitted to move through squares occupied by pieces of either color, except for the knight and during castling. When a king is under immediate attack, 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. There are three ways to counter a check: Castling
2544-452: The standard system today is short-form algebraic notation . In this system, each square is uniquely identified by a set of coordinates, a – h for the files followed by 1 – 8 for the ranks. The usual format is 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
2597-484: The tablebase, which initially (in 2014) required 140 TB of storage space and the use of a supercomputer but was later reduced down to 18.4 TB through the Syzygy tablebase. As of January 2023, the longest known forced mating sequence for the eight-piece tablebase (also ignoring the 50-move rule) was 584 moves. This was discovered in mid-2022 by Marc Bourzutschky. The eight-piece tablebase is currently incomplete, though, so it
2650-477: The two kings). One consequence of developing the seven-piece endgame tablebase is that many interesting theoretical chess endings have been found. The longest seven-piece example is a mate-in-549 position discovered in the Lomonosov tablebase by Guy Haworth, ignoring the 50-move rule . Such a position is beyond the ability of any human to solve, and no chess engine plays it correctly, either, without access to
2703-416: The two senses is known , nor is it expected that chess will be solved in the near future (if ever). Progress to date is extremely limited; there are tablebases of perfect endgame play with a small number of pieces (up to seven), and some chess variants have been solved at least weakly. Calculated estimates of game-tree complexity and state-space complexity of chess exist which provide a bird's eye view of
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#17327939844862756-463: The world every year catering to players of all levels. Tournaments with a small number of players may use the round-robin format, in which every player plays one game against every other player. For a large number of players, the Swiss system may be used, in which each player is paired against an opponent who has the same (or as similar as possible) score in each round. In either case, a player's score
2809-774: 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; these are held independently of FIDE. Solving chess No complete solution for chess in either of
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