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Checkers

Cocker Spaniel after whom Richard Nixon's renowned Checkers speech was named. Checkers is also the name of an American fast-food restaurant chain; see Checkers Drive-In.

This article is also not to be confused with Chequers, the official country residence of the Prime Minister of the United Kingdom

Checkers (or draughts) is a group of board games which involve the "jumping" of enemy pieces.

History

The game of draughts is thought to have originated in around 1100 AD, probably in southern France. It is thought the inventor created this board game by using a Chessboard, with the rules of Alquerque.

The pieces were originally called "ferses", the name that was given to chess queens at the time, and the draught ferses moved in the same way as the queen did in chess. Note however at this time, the queen was able only to move one square per turn. The one new move this game introduced was the ability to jump over opponent's pieces and take them. At this time the game was known as "Fierges".

In Philip Mouskat's "Chronique" (1243) is a reference to the use of "Kings" suggesting that the ability to promote a piece existed at this time.

When in Chess "ferses" were renamed to "Dame", the same occurred in Draughts, the games name also changed to "Dames". While it is thought that the original Fierges had a compulsory capture rule, there is no evidence that this rule existed in Dames. This rule was however reintroduced in France in the year 1535. Modern play includes this rule.

The name "Checkers" originated with European settlers in the United States.

Rules

Checkers (also known as Draughts) is played by two people, on opposite sides of a playing board, alternating moves.

The rules are:

• Board The Checkers board is an 8 by 8 grid, with alternating dark and light squares (forming a "checkered" pattern). The playable surface consists of the 32 dark squares only. A consequence of this is that, from each player's perspective, the left and right corners encourage different strategies.
• Pieces The pieces are usually made of wood and are flat and cylindrical. They are invariably split into one darker and one lighter color. Traditionally, these colors are Red and White. There are two kinds of pieces: normal and "king". King pieces are differentiated as consisting of two normal pieces, of the same color, stacked one on top of the other.
• Starting Position Each player starts with 12 pieces on the three rows closest to their own side, as shown in the diagram. The row closest to each player is called "King Row". The Red side moves first.
• How to Move There are two ways to move a piece: simply sliding a piece forward to an adjacent and unoccupied dark square or to "jump" a piece of the opposing player. It is possible for a piece to be "jumped" if on one side there is an opposing piece and the opposite side is vacant. In this case, one piece would "jump over" the other into the vacant square on the opposite side. A piece that is jumped is in essence captured: it is removed from the board. Multiple-jump moves are possible if when the jumping piece lands there is another opposing piece with a vacant square on the opposite side. Jumping is mandatory and cannot be passed up to make a non-jumping move, nor can fewer than the maximum jumps possible be taken in a multiple-jump move. If it is possible to make two jump moves, the player is free to choose which to make regardless of whether one is a multiple-jump move.
• Kings If a player's piece moves into the King Row on the opposing player's side of the board, that piece is said to be "kinged" and gains the ability to move in both forward and backward directions. If player's piece jumps into King Row, it cannot jump out (as in a multiple-jump move) until that move has ended and the piece has been kinged.
• How the Game Ends The first player to lose all of his or her pieces or to not be able to make a move loses the game. It is possible to lose the game without any pieces taken. A player may resign. A draw is called when it is not possible for either player to lose.

In tournament checkers, a variation called three-move restriction is preferred. The first three moves are drawn at random from a set of accepted openings. Two games are played with the chosen opening, each player having a turn at either side. This tends to reduce the number of draws and can make for more exciting matches. Three-move restriction has been played in the United States championship since 1934. A two-move restriction was used from 1900 until 1934 in the United States and in the British Isles until the 1950s. Before 1900, championships were played without restriction: this style is called go-as-you-please.

Computer Players

The first computer player of checkers was written in 1956 by Arthur Samuel, a researcher from IBM. Other than it being one of the most complicated game playing programs written at the time, it is also well known for being one of the first adaptive programs. It learned by playing games against modified versions of itself, with the victorious versions surviving. Samuel's program was far from mastering the game, although one win against a blind checkers master gave the general public the impression that it was very good. Samuel didn't mention his opponent was blind!

In the 1990s, the strongest program was Chinook written by a team led by Jonathan Schaeffer. Marion Tinsley, world champion from 1955-1962 and 1975-1991, won a match against the machine in 1992. In 1994, he had to resign in the middle of an even match because of health reasons; he died shortly thereafter. Chinook defended its man-machine title against Don Lafferty, and won the US national tournament in 1996 with a big margin. Chinook was retired after that tournament. The man-machine title was never contested again.

The best PC programs of today are stronger than the best humans, and also stronger than Chinook was at the time when it won the man-machine title. Today's PC's are much faster than the hardware Chinook ran on at the time thanks to Moore's law.

Computational complexity

It is a common misconception that checkers has been solved. The best computers can now beat all humans, but checkers is not yet completely solved. It is generally expected that checkers will be solved by 2010.

The number of legal positions in checkers is estimated to be 10¹⁸, and it has a game-tree complexity of approximately 10³¹.

When checkers is generalized so that it can be played on an n-by-n board, the problem of determining if the first player has a win in a given position is EXPTIME-complete.

Recently it was anounced that the tournament opening the White Doctor had been proved to be a draw.

Variants

• In Spanish/German/Russian checkers the kings can move as far as they want along any diagonal, like a bishop in chess; however, they cannot capture like a Bishop.
• In international draughts, (or international checkers), the board is 10x10 with 20 pieces each, and the kings move as far as they want on diagonals. Pieces can capture backwards. This is popular in the Netherlands, France, some parts of Africa and some parts of the former USSR and other eastern European countries. This is the most popular version of the game.
• In Turkish checkers pieces move straight forwards or sideways, kings moving like a rook in chess, so that both red and black squares are used. Each player starts with 16 pieces in the first two rows.
• In Halma pieces can move in any direction and jump over any other piece, friend or enemy. Pieces are not captured. Each player starts with 19 (2-player) or 13 (4-player) pieces all in one corner and tries to move them all into the opposite corner.
• Chinese Checkers is based on Halma, but uses a star-shaped board divided into triangles.

Famous Checkers Players

• Walter Hellman
• Asa Long
• Marion Tinsley

See also

• Chequers