CS 596 OODP: Checkers

CS 596 OODP
Checkers Description

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San Diego State University -- This page last updated Sept 26, 1995

Checkers or Draughts

Checkers or Draughts

The following is copied from The New Complete Hoyle by Morehead, Frey, Mott-Smith, 1956. The first variation described is sometimes called English draughts or regular checkers.

The Checker Board is identical with the Chess board - a large square composed of 8 x 8 smaller squares colored alternately dark and light. The board is set between the two players in the same orientation as for Chess; all play is conducted on the dark squares; consequently each player finds a double corner near his right hand. The distinction between double corner and single corner may be seen in Fig. 1.

The Checker Pieces are of uniform shape--wooden or composition disks at least one inch in diameter and a little less than half as thick. Each player is provided with twelve pieces of his own color. ( Actually, black and white checkers are rarely seen. The usual combinations of colors are black and red, or green and white. A set of Checker men always comprises fifteen pieces of each color, so that it will serve also for Backgammon.) The initial position of the pieces is shown in Fig. 1.

Figure 1. The Intial Position

PLAYERS

The players sit on opposite sides of the board. They are designated as Black and White, in accordance with the ( approximate ) color of the pieces used by each. There is unfortunately no uniformity of style in printing diagrams, as to whether the Black or White side is turned uppermost. In some books, Black is always uppermost; in others, White; in many periodicals, the side whose turn it is to move is placed at the bottom. The stipulation, such as "Black to move and win," thus indicates which way the board is turned.

Black invariably makes the first move, and thereafter the players move alternately.

THE PLAY

The movement of the pieces is simple. A piece may move diagonally forward one square, if that square is vacant. Or it may capture an adverse piece which is adjacent, diagonally forward, if the square next beyond that piece is vacant. The capture is executed by jumping over the adverse piece to the vacant square and removing the enemy from the board. If the capturing piece lands on a square from which another adverse piece is attacked in the same manner, it continues jumping, in the same turn, to capture all adverse pieces it can. A single man can capture a maximum of four pieces in one turn.

Away from the edge of the board, a piece can move in either of two directions. In a series of captures, a piece may change direction at will from each landing spot.

The primary rule of play is that, if able to do so, a player must capture rather than make a non-capturing move. Among several possible captures, a player may make a free choice. He is not compelled (as in Spanish Checkers) to capture two pieces in preference to one. But a capturing piece may come to rest only when unable to make any additional capture.

Crowning. All pieces on the board at the outset are single men. A single man may move only forward. The row of squares at the Black or White edge of the board is called the king row. On reaching the adverse king row, a single man is crowned and becomes a king. Its promotion is indicated by placing upon it a second checker of the same color. A player is required by law to crown the adverse pieces that reach his king row.

A king has the same powers of move and capture as a single man, plus the right to move backward as well as forward. If a single man reaches the king row by capture, it has to stop to be crowned; it may not continue capturing (as a king) in the same turn.

OBJECT OF PLAY

The object of play is to deprive the opponent of the ability to move in his turn. This is usually accomplished by capturing all twelve of his pieces, but it can also result from blocking his remaining pieces. The first player to find himself unable to move in turn loses the game.

A draw results only by agreement, each player being satisfied that he has no prospect of winning. If one player proposes a draw and the other refuses to abandon play, the latter must within forty moves demonstrate an increase in his advantage, or else concede the draw.

NOTATION

The notation used in recording games is based on numbering the squares as in Fig. 2. A move is denoted by the number of the square moved from, followed by the number of the square moved to, often joined by a hyphen. For example, the seven moves open to Black at his first turn are: 9-13, 9-14, 10-14, 10-15, 11-15, 11-16, 12-16. Moves may written linearly, as in this example, or in a column. No mark is attached to show whether a move is made by Black or White. So long as there are no kings on the board, the numbers themselves show the color of the move, for Black moves up and White down.

Figure 2. The Notation
An example of opening moves:

11-15
23-19
8-11
22-17
9-13
17-14
10-17
21-14

The last two moves are captures. No mark is used to indicate a capture; the fact of capture is (except in long king tours ) evident from the difference between the numbers. No noncapturing move can carry a piece to a square differing by more than 5.

A symbol much-used in annotation is the star ( * ). A starred move is the only one to win or to hold the draw.

VARIATIONS

Pyramid

Ten checkers are set up on each side, in the form of a pyramid. The Black pieces are on 1, 2, 3, 4, 6, 7, 8, 10, 11, 15. All men move only forward, do not crown, jump as in regular Checkers, but do not capture. That is, no pieces are removed from the board. It is compulsory to jump when able, and as far as able. The object of play is to maneuver one's own pieces to the squares originally occupied by the adverse pyramid. The first to do so wins. If in the course of play some pieces of one color are moved into a formation such that not all of them can get within the objective area, that color loses at once. For example, if White has moved pieces 3, 4, 8, and then is forced to jump 19-12, he loses, since the man on 12 cannot get inside the pyramid.

The Pyramid Game

Spanish Draughts

Spanish Draughts is like the English game with the following differences:

1. With a choice of captures, a player must capture the maximum possible of adverse pieces.

2. The king may move any distance along an open diagonal, and captures by jumping to the adjacent vacant square beyond an adverse piece, any distance away.

3. The double corner is placed at the players left.

Italian Draughts

Italian Draughts is like the English game with the following differences:

1. A single piece cannot capture a king.

2. With choice of captures, the player must capture with a king rather than with a single man, and must take the maximum of adverse pieces, and must take the most powerful if the number of adverse pieces concerned in the choice is the same.

3. The double corner is placed at the player's left.

Polish Droughts

Polish Droughts is little known in Poland. It probably was named in the same spirit as "Chinese Checkers" - to invoke the lure of the exotic. It is known to have been played in Paris as early as 1723. The board is 10 x 10, and each side has twenty pieces, set initially on the first four ranks. The rules are:

1. A single piece moves only forward ( diagonally ), but captures both forward and backward.

2. A single piece that reaches the king row by capture and finds an adverse piece adjacent ( with a vacant square beyond it ) must continue jumping in the same turn.

3. A single piece is crowned and becomes a king ( actually it is called a queen ) only when it reaches the king row and can legally stop there.

4. With a choice of captures, the player must take the maximum possible number of adverse pieces.

5. A king (queen) moves any distance along an open diagonal, and captures an adverse piece any distance away by landing on any vacant square beyond it on the same line. But the landing point must be chosen so as to enable the king to continue jumping, and with the maximum of captures, when there is any choice.

6. Each captured piece is removed from the board before the captor continues jumping; its removal may therefore open up additional captures previously impossible.

Turkish Draughts

Turkish Draughts differs from all other variants in that all 64 squares of the 8x 8 board are used. Each player has sixteen pieces, which are placed initially on the second and third ranks. The rules are:

1. A single man may move one square forward on the file, or diagonally forward, or sideward on the rank.

2. A single man captures in any of the same five directions; it must continue jumping so long as possible.

3. With choice of captures, the player must take the maximum number of adverse pieces.

4. A single man crowns on reaching the king row.

5. A king moves any distance on an open line in any direction, and captures by jumping to the adjacent vacant square beyond an adverse piece, any distance away.

6. Each captured piece is removed from the board before the captor continues jumping; its removal may therefore open up additional captures previously impossible.

Turkish Draughts