Doubling cube

Backgammon set, 19th century

To speed up match play and to provide an added dimension for strategy, a doubling cube is normally used. The doubling cube is a 6-sided die marked with the numbers 2, 4, 8, 16, 32 and 64. If a player believes his position to be superior he may, before rolling the dice on his turn, double, demanding that the game be played for twice the current stakes. The doubling cube is then placed with the 2 side face up to show that the game’s value has been doubled. His opponent must either accept the new stakes or resign the game immediately. Thereafter the right to redouble belongs exclusively to the player who last accepted a double. When this occurs, the cube is placed with the face of the next power of two showing.

The game is rarely redoubled beyond four times the original stake, but there is no theoretical limit on the number of doubles. Although 64 is the highest number depicted on the doubling cube, the stakes may rise to 128, 256, 512 and so on.

In money games, a player is often permitted to beaver when offered a double, doubling the value of the game again, while retaining possession of the cube.

The Jacoby rule allows gammons and backgammons to count for their respective double and triple values only if there has been at least one use of the doubling cube in the game. This encourages a player with a large lead in a game to double, possibly ending the game, rather than to play the game to its conclusion in hopes of a gammon or backgammon. The Jacoby Rule is widely used in money play but is not used in match play.

The Crawford rule is designed to make match play more equitable for the player in the lead. If a player is one point away from winning a match, his opponent has no incentive not to double; whether the game is worth one point or two, the outcome of the match is unaffected. To balance the situation, the Crawford rule requires that when a player first reaches a score one point short of winning the match, neither player may use the doubling cube for the following game, called the Crawford game. After the Crawford game, normal use of the doubling cube resumes. The Crawford rule is used in most match play.

Sometimes automatic doubles are used, meaning that any ties in the very first roll of the game automatically double the stakes. Thus, after a 3-3 roll, followed by a re-roll of 5-5, followed by a re-roll of 1-4 to begin the game itself, the game would be played for quadruple stakes. The doubling remains in the middle, with both players having access to it, and the Jacoby Rule is still in effect. Again, automatic doubles are common in money games. but they are rarely, if ever, used in match play.



<< Previous:Movement |Next:Variants >>

• This page was last modified 17:46, 21 December 2006.
• All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.)
  Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.