Tuesday, April 10, 2007

BackGammon Strategy And Tactics

Backgammon has an established opening theory, although it is less detailed than that of games like chess. The tree of checker positions expands rapidly because of the number of possible dice rolls and the moves available on each turn. Recent computer analysis has offered more insight on opening plays, but the midgame is reached quickly. After the opening, backgammon players frequently rely on some established general strategies, combining and switching among them to adapt to the changing conditions of a game.

The most direct strategy is simply to avoid being hit, trapped, or held in a stand-off. A "running game" describes a strategy of moving as quickly as possible around the board, and is most successful when a player is already ahead in the race. When this fails, a player may opt for a "holding game", maintaining control of a point on her opponent's side of the board, called an anchor. As the game progresses, this player may gain an advantage by hitting an opponent's blot from the anchor, or by rolling large doubles that allow the checkers to escape into a running game.

The "priming game" involves building a wall of checkers, called a prime, covering a number of consecutive points. This obstructs opposing checkers that are behind the prime. A checker trapped behind a six-point prime may not escape until the prime is broken. A particularly successful priming effort may lead to a "blitz", which is a strategy of covering the entire home board as quickly as possible while keeping one's opponent on the bar. Because the opponent has difficulty re-entering from the bar or escaping, a player can quickly gain a running advantage and win the game.

A "backgame" is a strategy of placing two or more anchors in an opponent's home board, while building a prime in one's own board. The anchors obstruct the opponent's checkers and create opportunities to hit them as they move home. The backgame is generally used only to salvage a game wherein a player is already significantly behind; using a backgame as an initial strategy is usually unsuccessful.

"Duplication" refers to the placement of checkers such that one's opponent needs the same dice rolls to achieve different goals. For example, a player may position all of her blots in such a way that her opponent must roll a 2 in order to hit any of them, reducing the probability of being hit. "Diversification" refers to a complementary tactic of placing one's own checkers in such a way that more numbers are useful.

Many positions require a measurement of a player's standing in the race, for example, in making a doubling cube decision, or in determining whether to run home and begin bearing off. The minimum total of dice rolls needed to move a player's checkers around and off the board is called the "pip count". The difference between the two players' pip counts is frequently used as a measure of the leader's racing advantage. Players often use mental calculation techniques to determine pip counts in live play.

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