In economics , perfect information (sometimes referred to as "no hidden information") is a feature of perfect competition . With perfect information in a market, all consumers and producers have complete and instantaneous knowledge of all market prices, their own utility, and own cost functions.
46-599: András Adorján (born András Jocha ; 31 March 1950 – 11 May 2023) was a Hungarian Chess Grandmaster (1973) and author. He adopted his mother's maiden name, Adorján, in 1968. In 1969–1970, Adorján secured the title of European Junior Champion at the 'Niemeyer Tournament' in Groningen , and in 1969 at Stockholm , he finished runner-up in the World Junior Chess Championship to Anatoly Karpov . His qualification as an International Master came in 1970 and as
92-556: A sequential game has perfect information if each player, when making any decision, is perfectly informed of all the events that have previously occurred, including the "initialization event" of the game (e.g. the starting hands of each player in a card game). Perfect information is importantly different from complete information , which implies common knowledge of each player's utility functions, payoffs, strategies and "types". A game with perfect information may or may not have complete information. Games where some aspect of play
138-713: A GM norm on offer?", to which came the answer "Yes". His next question—"When does it start?" was met with the reply "Half an hour ago". He also went on to win that tournament. At the Riga Interzonal of 1979, he finished joint third and qualified for the World Championship Candidates Tournament via tiebreaks, after drawing a match (+1 −1 =2) with fellow Hungarian Zoltán Ribli . At the Candidates he lost his quarter-final match to Robert Hübner . In team chess, Adorján had an excellent record. Competing at
184-450: A Grandmaster in 1973. The latter was also the year that he won (jointly) his first Hungarian Championship , going on to a further (this time outright) victory in 1984. Other tournament successes (finishing either first or joint first) included Varna 1972, Osijek 1978, Budapest 1982, Gjovik 1983, Esbjerg 1985 and New York Open 1987. In an interview, he recounts the story of his telephoned invitation to Luhacovice in 1973; he enquired—"Is there
230-408: 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
276-568: 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 the end of the 15th century, with standardization and universal acceptance by the end of the 19th century. Today, chess
322-607: 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
368-571: 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
414-511: 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,
460-505: 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)
506-476: 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
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#1733092950353552-971: Is hidden from opponents – such as the cards in poker and bridge – are examples of games with imperfect information . Chess is an example of a game with perfect information, as each player can see all the pieces on the board at all times. Other games with perfect information include tic-tac-toe , Reversi , checkers , and Go . Academic literature has not produced consensus on a standard definition of perfect information which defines whether games with chance, but no secret information , and games with simultaneous moves are games of perfect information. Games which are sequential (players alternate in moving) and which have chance events (with known probabilities to all players) but no secret information , are sometimes considered games of perfect information. This includes games such as backgammon and Monopoly . But there are some academic papers which do not regard such games as games of perfect information because
598-399: 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
644-415: 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
690-423: 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;
736-399: 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
782-411: 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
828-536: 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 is the current World Champion. A huge body of chess theory has developed since
874-430: 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 the game is to checkmate (threaten with inescapable capture) the enemy king. There are also several ways
920-422: 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
966-484: 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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#17330929503531012-526: 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
1058-530: The Chess Olympiad of 1978, he helped Hungary to capture the gold medal from the Soviet team who had convincingly won the event twelve consecutive times from 1952 through 1974. His further participation in 1984, 1986 and 1988 contributed to a top five finish on each occasion. Compatriots Lajos Portisch , Ribli and Gyula Sax were also at the peak of their playing strength during this period. Adorján also worked over
1104-817: 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 ,
1150-491: The black pieces— Black is OK , Black is Still OK and Black is OK Forever . The books challenge the popular perceptions of Black's chances and diagrammed positions are even presented with the black pieces playing up the board. For their creativity with the black pieces, Adorján cited the games of Tony Miles and Alexander Morozevich as a source of inspiration. In one review, it was suggested that Adorján's books could have been co-authored by Botvinnik and Monty Python . In
1196-404: 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
1242-448: 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
1288-473: The field of chess opening theory, Adorján's passions in many ways mirrored the theme of his books. Typical is his handling of the ' Hedgehog System' versus the English Opening . The system seeks to neutralise white's first move advantage by engineering rapid piece development on the queenside, behind flexible, low-key pawn moves (such as d6, a6 and b6). The formation is said to resemble the prickly spines of
1334-423: 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
1380-407: 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
1426-436: 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
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1472-409: 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 the first computer to beat a reigning World Champion in
1518-469: The hedgehog, repelling premature attacks and offering no soft targets . Adorján died on 11 May 2023, at the age of 73. Chess Chess 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
1564-414: 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
1610-442: 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
1656-427: 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
1702-443: 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,
1748-538: 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
1794-429: 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
1840-402: 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
1886-407: 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
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1932-415: 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
1978-452: 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
2024-459: 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
2070-669: 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. Perfect information In game theory ,
2116-466: The years, sometimes secretly, as a second to Garry Kasparov and to Peter Leko , helping them to prepare for important World Championship matches. He was known as a leading expert on the Grünfeld Defence , which was favored by both Kasparov and Leko. In later years Adorján played less and concentrated more on writing, becoming renowned for his series of books championing the cause of the player of
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