Backgammon Dictionary

Any technique for reducing the random error of a rollout. Examples are: quasi-random dice, duplicate dice, and luck reduction.

Luck reduction, a variance reduction technique that involves adjusting each trial's result based on an estimate of the luck associated with the rolls of the trial. Because luck reduction is by far the most effective technique for variance reduction, the term variance reduction is often used specifically to refer to this method. See posts by Jim Williams and David Montgomery.

Any game other than backgammon (1) which can be played on a backgammon board. Most backgammon variants use rolls of the dice to determine how the players' checkers move, just as in backgammon.

The Greek name for the exact equivalent of Western backgammon. Greek backgammon, called portes, is slightly different than vidos in that it is played without a doubling cube and has no bonus for winning a backgammon (2).

Vigorish.

The small additional considerations that affect the total equity of a position, such as gammon vigorish and recube vigorish.

A measure of how much a position's equity is likely to change in the next roll or two. See posts by Chuck Bower and Kit Woolsey.

A regular double, where one player offers to double the stakes of the game, as opposed an automatic double when identical numbers are thrown at the beginning of the game.

Purposely leave a blot within range of being hit now rather than be forced to leave it later when the danger may be greater.

Roll a prime.

A formula devised by Jeff Ward 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 Ward count is his pip count, plus 2 for each checker more than 2 on the one-point, minus 1 for each extra home-board point compared to the opponent, plus 2 for each extra checker on the board compared to the opponent, plus 1/2 pip for each extra checker outside the home-board compared to the opponent. Then the player on roll increases his count by 10 percent. Ward advises: Double if your count does not exceed the opponent's by more than 2; redouble if your count does not exceed the opponent's by more than 1; accept the double if your count does not exceed doubler's by more than 2 in a short race (50 pips), 3 in a medium race (75 pips), or 4 in a long race (100 pips). See post by Marty Storer. For a comparison with other methods, see the article, "Cube Handling In Noncontact Positions".

A blitzing (1) technique that involves switching points to hit an opposing blot.

["Wash" the slate clean.]  A settlement for zero points.

The expected loss in pips (2) from dice rolls not fully utilized during bearoff. Wastage is calculated as W = R x 49/6 − PC, where R is the expected (average) number rolls required to bear off, and PC is the pip count of the position. Wastage is the difference between the usual pip count and the effective pip count. See post by David Montgomery.

World Backgammon Association.  Website: WBA.

Worldwide Backgammon Federation.  Website: WBF.

A ploy which may be attempted when you are playing on for a gammon and the opponent gets a lucky roll. You offer to double even if your position is still too good, hoping the opponent will mistakenly accept. See this thread.

A checker play (2) error or cube play (2) error which costs more than 0.1 points of EMG equity; a blunder. See post by Daniel Murphy.

Blitz (1).

A straight race position in which a given roll played correctly induces the opponent to correctly double while an alternate (inferior) play would prevent the opponent from correctly doubling. This can happen when the correct play produces a position of greater volatility. Wisecarever paradox positions are examples of a cube provocation plays.

A rule of thumb advocated by backgammon expert Kit Woolsey: "If you are not absolutely sure whether a position is a take or a pass, then it is always correct to double." See The Doubling Rule, by Kit Woolsey.

[Or simply the "zone".]  Points 1 through 11 on your side of the board. The success of a blitz depends on the number of checkers you have in the zone. Usually 10 is enough to make a blitz worth trying.