“T” Backgammon Terms

The player who is behind in a match or behind in the race (2).  Compare: Leader.

Reaching the same position by different means.

A deliberate attempt to squeeze the opponent off of his anchor so that the trapper can close out any blots thereby exposed and win a gammon.

Traditional name for the three-point.

Playing a position out to the end of the game once (or to the point of truncation). A rollout consists of multiple trials, the results of which are averaged together to yield an estimate of the equity of the position.

Another name for the effective pip count, a concept developed by Walter Trice who wrote extensively about it.

[Named for Walter Trice.]  The ideal position to aim for during bear-in, consisting of: 7 checkers on your six-point, 5 checkers on your five-point, and 3 checkers on your four-point. It has the lowest wastage of any position with all 15 checkers still on the board.

A game popular in French high society prior to the Revolution. Players score points for making specific plays or moving their checkers into certain configurations.  See: How to Play Trictrac.

The French name for "backgammon."

Backgammon (2).

Traditional name for the three-point.

A rollout which is not played to the end of the game. Instead, the position is rolled out a given number of plies (the horizon of the rollout) and estimates of the equities of the resulting positions are averaged together. A truncated rollout has more systematic error than a full rollout but is faster because each trial is shorter, and a truncated rollout has less variance so fewer trials are required to converge on a result. See post by Gregg Cattanach.

The sequence of actions that each player takes in alternation. One turn consists of: (a) possibly offering a double; (b) rolling the dice; (c) playing the roll; and (d) picking up the dice.

A simple formula devised by Stephen Turner for estimating the match equity (1) at a given score. Expressed as a percent, the leader's match equity E = 50 + (24/T + 3) * D, where T is the number of points (4) the trailer still needs and D is the difference in scores.  Compare: Janowski's Formula and Neil's Numbers.

Move from the opponent's outer board to your own outer board.

To offer a double.

To offer a double.

A mode available in some backgammon-playing programs which allows the computer to evaluate your moves as you make them and alert you to any errors it thinks you made.

To offer a double.

The second point (1) in a player's home board, adjacent to the one-point; also called the deuce-point.

A bearoff database with the correct equity for each possible combination of two opposing bearoff positions. Four separate equities are recorded for each position: three cubeful equities (one for each state of the doubling cube), and one cubeless equity. A two-sided database is more accurate than a one-sided database, but requires considerably more room.