In Backgammon, Timing is Everything

In the backgammon position analyzed below, Black is on roll. The question is, should Black double? And if Black should double, should White take? Now, assuming it is a money game, or if you are a match player, let's say that the score is 0-0 in a match to 7.

The answer to both questions is yes; Black should double, and White should take. Known as a prime vs. prime situation, this situation is one of the most difficult to understand in backgammon. And the reason it is so difficult is timing.  

In this position, Black should double because if he rolls average numbers (the average roll is 8 pips), and White rolls average numbers, White will have to break his prime before Black. If White breaks his prime first, Black will be a strong favorite to win and could even win a gammon if things go really well. 

Black should double because if he waits until White breaks his prime and then doubles, it is too late - White would simply drop the cube and Black would win only 1 point instead of 2 or 4. 

Now, if White is likely to have to break his prime first, why should he take the cube? He should take the cube because some of the time Black rolls higher than average and White rolls lower than average and when that happens, Black breaks his prime first and it is Black who will probably lose or get gammoned. Even if Black holds his prime longer, White may not lose every time… he might get a shot and hit it and win the game that way. 

The theory for White, or anyone being doubled, is that they should not drop the cube just because they are losing…they should drop only when they are losing so much that they don’t have a reasonable chance to win.  

The key word is reasonable, and this is where it gets complicated. In money games, and in long backgammon matches where the score is tied, the person being doubled generally should take cubes if he has around a 25 percent or better chance to win. Of course, you have to take the risk of gammons and backgammons into consideration, and of course, how far along the game is matters quite a bit, as that affects the chances of getting to redouble at a later time in the game.  

All of these factors make backgammon a very complex game that takes years of study to truly master, and even then, only a few, very talented people have truly mastered the game. Take a look, for example, at the next position:

This backgammon position is identical to the position discussed earlier, except that Black’s checker on the 12 point is now on the 17 point. With 5 more pips to spare, the chances of Black having to break his prime before White have gone down enormously. In this situation, when Black doubles, White should pass. White has very little chance to win this game. In fact, if you put both positions into Snowie (a backgammon program) you will see that in Position 1 White should win about 26 percent of the time, and in position 2, it’s only about 18%. 

This position is identical to the former positions, except here Black’s checker in on his 3 point. In this position, Black should not even double. In fact, it’s almost exactly 50/50 as to who will win this game. If it was a money game, and Black would have doubled here, White should Beaver (turn the cube to 4 immediately) as White would be favored if he’s holding the cube. Holding the cube is an advantage, because the player holding the cube can redouble and win the game or increase the stakes (or risk) any time he is on roll, and the other player cannot. 

The big question is this: how do we know, when we are playing backgammon, that it’s a double and a take if the checkers are in one position, a double and drop in another, and not even a double in another position? The answer is: experience and study. 

The first position came up in a game I was playing recently, and because of my 45 years of experience and study I decided that I should double. Fortunately, I was playing Black at the time, and I say “fortunately” because even with all my experience and study, I was not sure if White should take or drop, and I only knew for sure after I put it in the computer and studied it further. The point is, the more you study the better you will know, but the exciting thing about backgammon is that you will often find yourself in positions where you just have to make your best guess. The only differences between the best backgammon players in the world and the rest of us are that their best guesses are better, and that they have to make guesses far less often.