Games: Backgammon

At first glance Black's position here does not look as if he can take a double from White, and in the chouette from which this position was taken, three of the team passed when doubled. One brave man took. He promptly escaped his back man with a 65, and White missed the shot and had to pass the subsequent redouble. But who was right?

Black has two things in his favour. He leads in the race by 51 pips and he still has a four-point board. However, if he can't escape his back man, the racing lead will become meaningless and his fragile home board will quickly deteriorate - he may even be forced to expose a second blot. There are many sequences where White will have lost his market by his next turn, so the double here is mandatory.

Has Black got enough winning variations to give him a take? His plan is to escape his back man and not get hit. On each roll he will have a 30 per cent chance of throwing a six and escaping from White's home board. If he hasn't escaped within three rolls he is likely to find himself either behind a six-point prime or on the bar facing a closed board. When White moves a man from his 21-point into the outer boards, Black can gain time by pointing on the remaining man, or by picking and passing (hitting and moving the blot to safety).

The answer to all of this is that Black will in fact win from this position 30 per cent of the time, giving him a reasonably comfortable take. If the spare man on his five-point were on his two-point he would have a borderline take, and if both the spare men on his five- and six-points were on his one- and two-points he would then have to drop. The flexibility provided by those two men in the original position turns out to be critical. This is an excellent benchmark position for "one man back" problems - file it for future use.