Problem - Solution

Match to 15 pts. White leads Black 11 to 8. White on roll. Cube actions?


White contemplates the cube for a minute and a quarter before rolling. Though slightly behind in the race, White has only one man back to Black's three, and three inside points to Black's two. White already dominates the outfield and his 15 hitting rolls eliminate Black's presence there entirely. Some of White's missing rolls (55, 44 and 22), allow him to make new blocking points in his outer court. In contrast, Black has an underdeveloped gap-toothed board with a spare already awkwardly deployed on the 3-point, and his checkers are widely separated. Against this, White has an inflexible position: seven points made; the race is close; and his four dancing rolls may prove costly.

White does well to consider doubling. If he hits and Black dances or reenters awkwardly, White loses his market. This occurs about one sixth of the time.

On his hitting rolls, White loses his market much of the time. On his 21 missing rolls, however, White will be better off not having doubled. These results alone make it too close to tell whether White should double.

We performed manual rollouts to test doubling versus waiting. Our results suggest that Senkiewicz is right not to double. Jellyfish favors waiting by an even wider margin. Our rollouts have White with an equity of +0.639 before doubling and with +0.600 after doubling. Jellyfish has White's equity as +0.635 before doubling and as +0.509 after doubling.

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Taken with permission from "Backgammon: Costa Rica 1993", by Ortega, Madrigal and Kleinman.


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Created by Max. Updated November 20, 1997.