Here's a difficult position that generated the playing of a proposition at the Double Fives Club. White, who was the box in a three-handed chouette, has just been hit and failed to enter his man from the bar. This is a classic redoubling situation where the roll of any 3 by us, played 23/20, will lose our market. My partner and I immediately redoubled and after some mutterings the box passed, giving us two points each. His fear of the gammon was obviously the key deciding factor in his deliberations.

No sooner had he passed than he offered to play the position as a proposition. To remind you of what happens: the doubling side pays the taking side a point to take the cube on two, and the two players agree to play a specific number of games. In this case my partner played 30 games against the box and won 39 points. Subtracting the 30 points he paid up front left him with a net profit of 9 points, so it looked from this short proposition as if the position is a drop.

That evening I had Jellyfish 3.0 play out the position 5,000 times. Black won only 52 per cent of the games but 32 per cent were gammons. Simple arithmetic shows that if White takes the redouble he will lose 144 points in 100 games, while if he drops the redouble he will lose 200 points. Thus it is clear that the position is a take, and by a reasonable margin. There are two things to be learnt here. First, this sort of position is not directly calculable so it is a useful reference to remember for future use. Second, if the box thought it was a take and then wanted to play it as a proposition why on earth didn't he take the original redouble? The answer is that the dread of a gammon in the box is one of the primal fears in backgammon - use it to advantage whenever you can!