Backgammon Dictionary

In money play with the doubling cube, the absolute value of a position to one of the players compared to the initial stake being played for.  See: Equity. Cubeful equity considers the current value of the cube, cube ownership, and the potential for future doubles. In match play, cubeful equity corresponds to the probability of winning the match from the current position.  Compare: Cubeless Equity.

A rollout performed with the doubling cube in play. All appropriate cube decisions are made as the position is played out. That means some trials will end in a dropped double and others will end with the cube at 2, or 4, or even higher. Cubeful rollouts more accurately simulate actual games than cubeless rollouts, but they have greater variance, so they do not converge as quickly. And cubeful rollouts may be more susceptible to systematic error because of cube misplays.

The value of a position if the game is played without a doubling cube. This is a value between -3 and +3 and is equal to P(W) + P(Wg) + P(Wbg) - P(L) - P(Lg) - P(Lbg), where P(W) is the probability of winning the game, P(Wg) is the probability of winning a gammon (or backgammon), P(Wbg) is the probability of winning a backgammon, P(L) is the probability of losing the game, P(Lg) is the probability of losing a gammon (or backgammon), P(Lbg) is the probability of losing a backgammon.  Compare: Cubeful Equity.

The chance of winning the game if no doubling cube is used; also called game winning chances.

A rollout performed without using a doubling cube. Each trial is played to the end of the game and scored plus or minus 1, 2, or 3 points (4) depending on whether gamed ended in a single game, gammon, or backgammon (2). Because cubeless rollouts do not include cube play, they do not perfectly simulate a game, but cubeless rollouts have less variance and less systematic error than cubeful rollouts.

The act of offering a double, or the act of accepting or refusing the opponent's double.

The art or skill of making cube decisions.  Compare: Checker Play (2).

An error in checker play that induces the opponent to double on his turn. The ploy could be intentional, an attempt to get the opponent to double too early, but the term "cube provocation play" is often used mockingly to refer to an obvious error.   See:  Danny Kleinman (1980) "Cube Provocation Play".

A correct checker play that leads the opponent to correctly double when at least one other play is available after which the opponent would be wrong to double. This can happen if the better play produces a more volatile position -- the opponent is forced to double because he has too many market losers. Examples are Wisecarver Paradox positions.

A player in a chouette who temporarily handles the cube for another while that player is away from the game. See post by Ilia Guzei.

A position for which the correct cube action is known which serves as a standard by which other similar positions may be judged. See post by Chuck Bower.

Dice cup.

The initial stake multiplied by the value of the doubling cube.

[From the action a player makes as he first reaches to enter his checker then pulls his arm back when he notices the numbers are blocked.]  To throw numbers which fail to enter a checker from the bar.

Danish Backgammon Federation.   Website: www.dbgf.dk.

A spare checker deep in the player's home board where it serves no useful purpose.  See: Bury a Checker.

A doubling cube with no further doubling value. In match play, the cube is said to be dead when the player owning the cube has no reason to double. For example, a player who owns a 2-cube when he is two points (4) away from winning the match will never double because he can win the match with the cube at its current level.

Dead checker.

A specific number on the dice which cannot be played in the current position; see kill a number.

Refuse a double.

On a low-numbered point (1), usually the one-point or two-point.

An anchor on the opponent's one-point or two-point.