Primes

# The Prime Syndrome Gaby Horowitz and Dr. Bruce Roman, 1983

 From Backgammon Times, Volume 3, Number 3, Fall 1983.

Students of the game of backgammon have long been taught and even conditioned to build and maintain primes. Backgammon is a game of escape and entrapment. Primes are very effective vehicles for entrapping your opponent. But, as most of us have learned at some point in our lives, too much of a good thing can be harmful. So it is with primes.

There seem to be two main reasons why a majority of players become obsessed with primes: (1) a feeling of security, and (2) aesthetics. It is true that primes are pleasing to the eye, but pluses on the score sheet are even more so!

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Position 1.
Black to play 5-3.
In Position 1 it seems correct to make the 5 point, creating a solid 5-point prime. Black, however, does not need a 5-point prime to win the game or to gammon White. It is much more important to stop White from making the 1 point, which would allow him to stay in the game to the end and probably give him one or two winning shots at Black while Black is bearing off. The correct move is 6/1*, 4/1 (Position 1a).
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Position 1a.
After 6/1*, 4/1.
White has one roll in which to establish an anchor with either move. But an anchor on the 5 point will be much less effective for getting a shot because Black will only have to clear the 6 point by the time White reenters his men.

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Position 2.
Black to play 2-1.
In Position 2 the only way Black can win the game is to get both of White's men on the bar against a closed board. Black must break his prime to allow White to split his remaining two men. Most players would break the prime by clearing the bar point, hoping White will throw a 5. This is incorrect because: (1) If White does not throw a 5 in the next few rolls, Black will advance his hunters who are needed where they are to hit White as he escapes; (2) Black will pay off to 5-5; and (3) Since White is defenseless (he has no board) Black does not need a perfect distribution of builders to hit him because even if White return hits, Black will come in immediately. The correct move is 8/6, 4/3 (Position 2a).
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Position 2a.
After 8/6, 4/3.
This move will force White to split his men with any 2 (the same 11 chances as he would have to throw a 5) but, should he roll his very best number (2-2), Black still does not lose the game.

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Position 3.
Black to play 2-1.
In Position 3 it looks as though Black is well on his way to the bank. When the position is this good we usually see two different extremes in play:

1. A tendency by experienced players to "overplay" the position by trying to anticipate future rolls further than they should in order to achieve a "perfect" bearoff.

2. Carelessness by the inexperienced player in not protecting against large doubles.
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Position 3a.
After 6/4, 6/5.
The safest move is 6/4, 6/5 (Position 3a), breaking the prime now at your convenience and not being forced to break it later at the discretion of the dice. This also allows Black to smooth out his distribution by being able to play large and small numbers comfortably.

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Position 4.
Black to play 1-1.
Has Black gotten too greedy by hitting too many blots (Position 4)? Not if he plays the 1-1 correctly. It would be incorrect to make the 6 point because this would prevent White from coming in and so increasing his chances of getting a shot. Black should want White to enter his men and so should play 5/4, 5/3, 11/10 (Position 4a).
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Position 4a.
After 5/4, 5/3, 11/10.
He can now peacefully bear his remaining men in, creating a sound distribution from which to bear off safely. This considerably decreases White's chances of getting a winning shot.

 More articles by Gaby Horowitz More articles by Bruce Roman More articles on primes Return to:  Backgammon Galore