Chess

Chess
	The Chess Pieces From left, a white king, black rook and queen, white pawn, black knight, and white bishop in a set of Staunton chess pieces.
Players	2
Setup time	30-60 seconds
Playing time	Typically 10-60 minutes, but highly variable. A game can last anywhere from seconds to years! Clocks are used in competition to limit the playing time.
Chance	None
Age range	Recommended for 8 years or older.
Skills	Tactics, Strategy

For other meanings, see Chess (disambiguation).

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Chess Starting position

Chess is a board game and mental-skill game for two players. It is played on a square board of eight rows (called ranks) and eight columns (called files), giving 64 squares of alternating colour, light and dark, with each player having a light square at the near right corner when facing the board. Each player begins the game with 16 pieces which can move in defined directions (and in some instances, limited range) and can remove other pieces from the board: each player's pieces comprise eight pawns, two knights, two bishops, two rooks, one queen and one king. One player controls the white pieces; the other player controls the black pieces (The player that controls white is always the first player to move).

In chess, when a player's king is directly threatened by one or more of the opponent's pieces, the player is said to be in 'check'. When in check, only moves that can evade check, block check or take the offending piece are permitted. The object of the game is to checkmate the opponent; this occurs when the opponent's king is in check, and no move can be made that would escape from check.

Introduction

Chess is not a game of chance; it is based solely on tactics and strategy. Nevertheless, the game is so complex that not even the best players can consider all contingencies: although only 64 squares and 32 pieces are on the board, the number of possible games that can be played far exceeds the number of atoms in the universe (see Shannon number).

Chess is one of the world's most popular games; it has been described not only as a game but also as an art and a science. Chess is sometimes seen as an abstract wargame; as a "mental martial art", and teaching chess has been advocated as a way of enhancing mental prowess. Chess is played both recreationally and competitively in clubs, tournaments, online, and by mail (correspondence chess). Many variants and relatives of chess are played throughout the world. The most popular, in descending order by number of players, are xiangqi in China, shogi in Japan, and janggi in Korea.

History

Main article: Origins of chess

A chess table is a table with a chessboard painted or engraved on it. The photograph shows a chess table in a park.

File:Chess central park 1946.jpg

Two men playing chess on a Central Park bench in New York City, May 1946.

Many countries claim to have invented the chess game in some incipient form. The most commonly held belief is that chess originated in India, where it was called Chaturanga, which appears to have been invented in the 6th century AD. Although this is commonly believed, it is thought that Persians created a more modern version of the game after the Indians. In fact, the oldest known chess pieces have been found in excavations of ancient Persian territories.

Another theory exists that chess arose from the similar game of Chinese chess, or at least a predecessor thereof, existing in China since the 2nd century BC. Joseph Needham and David Li are two of many scholars who have favored this theory.

Chess eventually spread westward to Europe and eastward as far as Japan, spawning variants as it went. One theory suggests that it migrated from India to Persia, where its terminology was translated into Persian, and its name changed to chatrang. The entrance of chess into Europe, notably, is marked by a massive improvement in the powers of the queen. The oldest known texts describing chess seem to indicate a bi-directional spread from the Persian empire. In fact, the oldest known reference points to Shah Ardashir as being a master of the game, his rule was from 224 - 241 AD. This would indicate that chess was invented some time before his rule.

From Persia it entered the Islamic world, where the names of its pieces largely remained in their Persian forms in early Islamic times. Its name became shatranj, which continued in Spanish as ajedrez and in Greek as zatrikion, but in most of Europe was replaced by versions of the Persian word shāh = "king".

There is a theory that this name replacement happened because, before the game of chess came to Europe, merchants coming to Europe brought ornamental chess kings as curiosities and with them their name shāh, which Europeans mispronounced in various ways.

checkmate: This is the English rendition of shāh māt, which is Persian for "the king is finished".
rook: From the Persian rukh, which means "chariot", but also means "cheek" (part of the face). The piece resembles a siege tower. It is also believed that it was named after the mythical Persian bird of great power called the roc.
bishop. From the Persian pīl means "the elephant", but in Europe and the western part of the Islamic world people knew little or nothing about elephants, and the name of the chessman entered Western Europe as Latin alfinus and similar, a word with no other meaning (in Spanish, for example, it evolved to the name "alfil"). This word "alfil" is actually the Arabic for "elephant" hence the Spanish word would most certainly have been taken from the Islamic provinces of Spain. The English name "bishop" is a rename inspired by the conventional shape of the piece. In Russia, the piece is, however, known as слон = "elephant".
queen. Persian farzīn = "vizier" became Arabic firzān, which entered western European languages as forms such as alfferza, fers, etc but was later replaced by "queen".

The game spread throughout the Islamic world after the Muslim conquest of Persia. Chess eventually reached Russia via Mongolia, where it was played at the beginning of the 7th century. It was introduced into Spain by the Moors in the 10th century, and described in a famous 13th century manuscript covering chess, backgammon, and dice named the Libro de los juegos. Chess also found its way across Siberia into Alaska.

Gameplay

Rules of chess

Name	Letter	Picture
Pawn	None
Knight	N
Bishop	B
Rook	R
Queen	Q
King	K

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The eight queens puzzle is the problem of putting eight queens onto a chessboard such that none of them is attacking any other. This is one of twelve solutions.

See Rules of chess for some important details not covered here.

When a game of chess begins, one player controls the sixteen white pieces while the other uses the sixteen black pieces. The colors are chosen either by a friendly agreement, by a game of chance, or by a tournament director. White always moves first and therefore has a slight advantage over black. The chess pieces should be set up on a standard chessboard with a white square in the near right hand corner.

Each kind of chess piece moves a different way. The rook moves any number of spaces vertically or horizontally, while the bishop moves any number of spaces in any direction diagonally (meaning a bishop will always remain on the same color). The queen is a combination of the rook and bishop (it can move any number of spaces diagonally, horizontally, or vertically). The king can move only one square horizontally, vertically, or diagonally. The knight can jump over occupied squares and moves two spaces horizontally and one space vertically (or vice versa), making an L shape; a knight in the middle of the board has eight squares it can move to.

With the exception of the knight, pieces cannot jump over each other. One's own pieces ("friendly pieces") cannot be passed if they are in the line of movement, and a friendly piece can never replace another friendly piece. Enemy pieces cannot be passed, but they can be "captured". When a piece is captured (or taken), the attacking piece replaces the enemy piece on its square (en passant being the only exception). The king cannot be captured in regular chess, only put in check. If a player is unable to get their king out of check it is called checkmate and they have lost the game.

Pawns capture differently than they move; they can capture an enemy piece on either of the two spaces adjacent to the space in front of them (i.e., the two squares diagonally in front of them), but cannot move to these spaces if they are vacant; conversely, a pawn can move forward one square, but only if that square is unoccupied. Alternatively, a pawn can move two squares forward if it has not moved yet and both squares are empty. If a pawn advances all the way to the eighth rank, it can be promoted to any other piece, except a King.

Chess games do not have to end in checkmate. Either player may resign if the situation looks hopeless; also, games may end in a draw (tie). A draw can occur in many situations, including mutual agreement to draw, draw by insufficient material, stalemate, threefold repetition or the fifty move rule. Draws are very common among high-level chess players and the majority of games between GM's are drawn. Nunn article has a good summary of the situation and his proposal is to simply not invite players who draw a lot to tournaments. The following is a summary of the other known proposed solutions:

1. Sophia rules, where draw offers are not allowed before move 30. Also used by the HB Global tournament. This method does reduce the short draws, but if both players trade off pieces, they can essentially agree to a draw, without a draw offer.

2. Proposed cure for severe acute drawitis by FIDE officials Eliminates draws completely by forcing a fast time control game to be played after a draw to ensure there is always a winner and a loser. One potential issue for this proposal is that both players can quickly agree to a draw in the tournament game and then play a speed chess game to decide things. The FIDE 128 player tournament has seen many matches where the two tournament time control games are drawn and advancement is decided by rapid (30 minutes for a game) or blitz (5 minutes) games.

3. BAP System makes it undesirable for one or both players to agree to a draw by changing the point value of win/loss/draw based on color played. 3 points for black win, 2 points for white win, 1 point for black draw, 0 points for white draw or any loss. Only one tournament [Bainbridge Slugfest tournament games] has been played under BAP, so there is not enough data to make firm conclusions with. However, there were no short draws in the Bainbridge Slugfest and all the draws were fighting draws.

4. 10 move rule has also been proposed where a draw offer that has been made is "on the table" for 10 moves.

5. Letting the computer arbitrate it by having a strong computer program evaluate the drawn position. An offshoot of this is the "Prove it" proposal where both players that agreed to a draw play out the game at a fast time control against a strong computer chess program.

6. Russell Miller [Chess Skins Proposal] proposed a chess skins game, where the points for the draw go to the next round. Draws would not directly be discouraged, but it would not be logical to settle for a draw if there are winning chances. Please update this section if you know of a tournament that used this method.

7. Other proposals that change the actual rules of chess have little chance of getting widely adopted. If you know of other proposals, please update here.

Strategy and tactics

For more details on this topic, see Chess strategy and tactics.

Chess openings are a sequence of moves, often memorized, which will help a player build up their position and prepare for the middlegame. Openings are often designed to take hold of the center of the board (e4, e5, d4 and d5), develop pieces, protect the king, and create a strong pawn structure. Hypermodernism advocates the control of the center not by using pawns but with distant pieces. It is often important for a player to castle (a special move that moves the king from the center of the board two squares towards one of the corners) to protect the king. See the list of chess openings for more information.

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The black knight on e6 is pinned to its king by the white bishop and the white knight is pinned to the queen on b1.

When taking and trading pieces, the chess piece point values becomes important. Valuations differ slightly from book to book, but generally, queens are worth 9 points, rooks are worth 5, bishops and knights are worth 3, and pawns are worth 1. Since the king's loss ends the game it is invaluable. The actual value and importance of a piece will vary based upon its position. If a player performs a sacrifice (e.g. exchange sacrifice), they are choosing to ignore the standard valuation of their pieces for positional or tactical gains.

A few positional elements common to most chess tactics are forks and traps. A fork is a situation where a piece is moved such that it attacks (forks) two other pieces simultaneously. It usually is difficult for the other player to protect both of their pieces in one move. Pins are used to prevent the movement of an enemy piece by threatening any pieces behind it should it move. Skewers are a kind of reverse pin where the more valuable piece is placed in front of a less important one. A discovered attack is an attack where a piece moves and uncovers a line for another piece which does the attacking. Other tactical elements include: zwischenzug, undermining, overloading, and interference.

During the endgame, pawns and kings become relatively more powerful pieces as both sides often try to promote their pawns. If one player has a large material advantage, checkmate may happen quickly in the endgame. If the game is relatively even, tablebases and endgame study are essential. Controlling the tempo (time used by each move) becomes especially important when fewer pieces are left on the board. In some cases, a player will have a material advantage, but will not have enough material to force a checkmate.

Ways to play chess

Blitz chess is a version of chess where a chess clock is used to limit the time control for each player. Generally each side has three to fifteen minutes (five is common) for all of their moves. An even faster version of chess is known as bullet chess or lightning chess. Bullet chess's time controls are less than three minutes. Speed chess requires the player to spend less time thinking because if the player's time runs out they lose. When playing at faster time controls computers become relatively more powerful to humans.

When two players are separated by great distances they can still play chess. Correspondence chess is chess played through the mail, e-mail or special Correspondence Chess Servers. Today, chess is often played on the internet through the Internet Chess Club, Yahoo! Games or another host.

Modern chess

Early on, the pieces in European chess had limited movement; bishops could only move by jumping exactly two spaces diagonally (similar to the elephant in xiangqi), the queen could move only one space diagonally, pawns could not move two spaces on their first move, and there was no castling. By the end of the 15th century, the modern rules for the basic moves had been adopted from Italy: pawns gained the option of moving two squares on their first move and the en passant capture therewith, bishops acquired their modern move, and the queen was made the most powerful piece; consequently modern chess was referred to as "Queen's Chess" or "Mad Queen Chess." The game in Europe since that time has been almost the same as is played today. The current rules were finalized in the early 19th century, except for the exact conditions for a draw.

The most popular piece design, the "Staunton" set, was created by Nathaniel Cook in 1849, endorsed by Howard Staunton, a leading player of the time, and officially adopted by Fédération Internationale des Échecs (FIDE) in 1924.

Chess's international governing body is FIDE, which has presided over the world championship matches for decades. See World Chess Championship for details and a more in-depth history. Most countries of the world have a national chess organization as well. Although chess is not an Olympic sport, it has its own Olympiad, held every two years as a team event.

Notation

Until the 1970s, at least in English-speaking countries, chess games were recorded and published using descriptive chess notation. This has been supplanted by the more compact algebraic chess notation. Several notations have emerged, based upon algebraic chess notation, for recording chess games in a format suitable for computer processing. Of these, Portable Game Notation (PGN) is the most common. Apart from recording games, there is also a notation Forsyth-Edwards Notation for recording specific positions. This is useful for adjourning a game to resume later or for conveying chess problem positions without a diagram.

Chess and education

There is a flourishing movement to use the game of chess as a tool to aid the intellectual development of young people. Encouraged by the promising results of a number of research studies, school districts and organizations across the globe are implementing chess programs.

New York based Chess-In-The-Schools, Inc.,[1]. has been active in the public school system in the city since 1986. They currently reach more than 30,000 students annually. The Americas Foundation for Chess[2] has initiated programs in partnership with local school districts in several US cities, including Seattle, San Diego, Philadelphia and Tampa.

At the collegiate level, the University of Texas at Dallas and the University of Maryland Baltimore County, both recruit chessplayer-scholars, and run scholastic outreach programs in their respective communities.

Computer chess

Main article: Computer chess

Serious work on machines that play chess has been going on since 1890, and chess-playing computer programs featured prominently in the artificial intelligence boom of the 1950s - 1970s. At first considered only a curiosity, the best chess playing programs — like Shredder, Fritz etc. — have become extremely strong players. In blitz chess, they can beat the best human players; at regular time controls, however, battles between the very best chess programs and the very best human players have been tantalizingly finely balanced. However, it is important to note that the method by which computer programs play chess does not really resemble the way humans play chess — the computer basically just calculates the board position after every possible combination of legal moves and acts accordingly, whereas human masters act more from intuition and pattern recognition. Moreover, as CPU speed and memory become less expensive, computer chess programs can search ever larger numbers of moves in the same amount of time, and store ever larger databases of opening and endgame positions. Nor has the study of chess proven particularly useful in the broader AI field; the methods used to play high-level chess are very different to the ones used for machine learning, machine vision, and the like.

Garry Kasparov, then ranked number one in the world, played a six-game match against IBM's chess computer Deep Blue in February 1996. Deep Blue shocked the world by winning the first game in Deep Blue - Kasparov, 1996, Game 1, but Kasparov convincingly won the match by winning three games and drawing two.

The six-game rematch in May 1997 was won by the machine (informally dubbed Deeper Blue) which was subsequently retired by IBM. In October 2002, Vladimir Kramnik drew in an eight-game match with the computer program Deep Fritz. In 2003, Kasparov drew both a six-game match with the computer program Deep Junior in February, and a four-game match against X3D Fritz in November.

The chess machine Hydra is the intellectual descendant of Deep Blue; and appears to be somewhat stronger than Deep Blue was. Certainly it is very much comparable in terms of positions analysed per second. Given the relative ease with which it beats the other programs, and the humans it has met, Hydra may be expected to beat any unaided human player in match play. In June 2005, Hydra scored a decisive victory over the then 7th ranked GM Michael Adams winning five games and drawing one game in a six game match. Whilst too few games have been played to establish this, and neither Kramnik or Kasparov have played Hydra, Hydra's creators estimate its rating should be over 3000.

Kasparov's loss to Deep Blue has inspired the creation of chess variants in which human intelligence can still overpower computer calculation. In particular Arimaa, which is played upon a standard 8×8 chessboard, is a game at which humans can beat the best efforts of programmers so far, even at fast time controls.

Chess variants

For more details on this topic, see Chess variant.

Chess variants are forms of chess where the game is played with a different board, special fairy pieces or different rules. There are over 1500 unique variants of chess. Bobby Fischer noted the overemphasis on memorizing chess openings in normal chess and invented Fischer Random Chess. Fischer Random Chess and other versions with different starting positions work by scrambling the initial starting position for every game. See the list of chess variants for more details.

References

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- Reprint: (1996) ISBN 0192800493
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External links

Learning chess

Official FIDE rules
Chess.FM - annotated grandmaster games and tutorials

Chess news

Internet servers to play chess

Free internet chess server (FICS) with over 150000 registered users, is one of the oldest and one of the largest non-commercial internet chess servers.
Playchess.com - one of the largest commercial chess servers with more then 3000 players online each night.
BrainKing.com - server, which besides chess allows to play a lot of chess variants.
Internet Chess Club - A competitive chess server with 30,000 members worldwide and 500 free tournaments each week. It also has the most grandmasters registered of any online chess server.

Collections of games

ChessGames.com - online chess database and community
ChessBase online database - games are filtered by year, player, opening, etc..
Chesslab.com - search by opening, player, results, position etc.
Chess games links - collection of links to chess games, which can be downloaded for free

Free chess software

Chess programs & utilities - large collection of links to all sorts of chess software
Aaron's chess engines FAQ
Chessopolis - freeware chess engines
ChessBase Light - older version of Chessbase, which allows to view games in CBH and PGN format.
Winboard