Backgammon Dictionary

The standard deviation of the difference between two rollouts: JSD = sqrt(SD1*SD1 + SD2*SD2). A measure of how statistically significant the result is.

An exceptionally good roll, especially a roll that reverses the likely outcome of the game; a roll much luckier than average.

Joint standard deviation.

Affectionate name for a player's farthest-back checker.

Breaking points in your home board in hopes of getting the checkers recirculated, a back game strategy.

A position which is both a proper double and a correct beaver. This can happen only in money play with the Jacoby rule. By doubling, the underdog gets full value for his potential gammons, thus raising his equity; however, as long as this equity remains negative, the opponent should beaver.

A formula devised by Tom Keith for making cube decisions in pure race games. It is a modification of the basic pip count designed to take into account elements of checker distribution. Each player's Keith count is his pip count, plus 2 for each checker more than 1 on his one-point, plus 1 for each each checker more than 1 on his two-point, plus 1 for each checker more than 3 on his three-point, plus 1 for each empty space on points four, five, or six. Then the player on roll increases his count by one-seventh (rounding down). Keith advises: Double if your count exceeds your opponent's count by no more than 4; redouble if your count exceeds your opponent's count by no more than 3; take if doubler's count exceeds your count by at least 2. For a comparison with other methods, see the article, "Cube Handling In Noncontact Positions".

A point (1) required to complete a prime in front of the opponent's runners; the four-point, five-point, and bar-point are usually key points.

To watch a game or match.

To make a comment during the game within hearing distance of the players (undesirable behavior in a tournament).

Spectator to a game. Good etiquette dictates that kibitzers not discuss the game within earshot of the players.

To move an extra checker deep within your home board where it serves no useful purpose.  See: Dead Checker.

To create a position in which a specific number on the dice cannot be played on the following turn. Killing 6's, for example, is a way to preserve your timing in a priming battle or when defending against a back game.  Compare: Save a Number.

[Proposed by Danny Kleinman.]  A guideline for cube handling in pure race positions. Compute K = (D+4)*(D+4) / (S-4), where D is the player's pip count minus the opponent's count, and S is the sum of the pip counts. Kleinman says a player should make an initial double if K > 0.44, or redouble if K > 0.61, and the opponent should accept a double or redouble if K < 1.2. See post by: Øystein Johansen.

Hit a checker.

A type of tournament where you continue to play until you lose; an elimination tournament.

An ongoing competition in which players are ranked in approximate order of ability. Any player may challenge another player higher on the ladder, up to a given number of steps away. If the challenger wins, he moves up the ladder and his opponent moves down.

Flight.

A player's last opportunity to make a throw which will give him a chance of winning the game or saving a gammon. (From Philipp Martyn on Backgammon, p. 186.)

A tournament for players who lose in the first rounds of the consolation flight or later rounds in the main flight.

A position in which the next roll will decide the game. In a last roll position, you should double if you have greater than 50% game winning chances and your opponent should accept your double if he has greater than 25% game winning chances.

[Named after Andy Latto, who suggested the possibility in an Inside Backgammon article, (Vol. 2, No. 3).]  A position which is a correct redouble but not a correct initial double. See post by Jean-Pierre Seiman.