I have been working recently with a program that calculates the expected number of rolls remaining in a non-contact race.
The program does not consider the opponent’s position. It seeks only to minimize the number of rolls left for the player who is on roll. This means that it cannot adjust for last-roll cirmcumstances where a player needs doubles, nor can it modify its strategy based on the position of the doubling cube or gammon considerations.
For the most part, the program recommends moves that are spot on. I’ve learned, for instance, that in many bear-off situations where an ace can be played from either the three point or the two,
it is better to have two checkers on the two point than one on the one (and the two point bare). Here are two examples:
X to play 5-1
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Move . . . . . Rolls Remaining
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4/off, 3/2 . . . . . 1.8642
4/off, 2/1 . . . . . 1.89198
4/off . . . . . . . . 1.91975
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X to play 6-1
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Move . . . . . Rolls Remaining
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6/off, 3/2 . . . . 1.88889
6/off, 2/1 . . . . 1.90432
6/off, 4/3 . . . . 1.91975
6/off . . . . . . . 1.9375
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Every now and again, however, the program comes up with a move that GNUBG rollouts will not confirm. In the position below, for example, my impulse (and GNUBG’s) is to slot the three point:
X to play 2-1
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Move . . . . . Rolls Remaining
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5/2 . . . . . . . . 10.1854
5/3, 4/3 . . . . . 10.1989
6/3 . . . . . . . . 10.2011
4/2, 4/3 . . . . . 10.2036
5/3, 5/4 . . . . . 10.2058
6/4, 5/4 . . . . . 10.2061
6/4, 6/5 . . . . . 10.2191
6/5, 4/2 . . . . . 10.2351
4/1 . . . . . . . . 10.2372
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Does this match up with your experience? Is the program making errors?