Magriel's NYT Columns |
The diagrammed position is taken from the last game of the 17-point consolation finals. Gilbert (Black) had built a commanding 16–5 lead against Trigg (White). With the Crawford Rule no longer in effect, Trigg had doubled on the opening roll. Black has escaped with both his back men and is now in a favorable position. However, White, with four men in Black’s home board, still has good potential to play a back game and hope to hit Black on his way home.
5
MATCH TO 17 16 |
| Black to play 5-1. |
The obvious play is 8/7*, 16/11, hitting White’s annoying man on the 7-point. Unfortunately, this gives White too many return shots. White will, in fact, be a favorite to hit back because effectively he has a double shot at Black; almost all 5’s and 6’s enable White both to reenter and hit. By employing the duplication principle, Gilbert found a play that was both safer and more constructive.
The number that White needs to hit with, 4, is said to be “duplicated.” By duplicating White’s good numbers, Black greatly reduces his chance of being hit. (He is effectively leaving a single direct shot instead of a double direct shot.)
In general, if you must leave blots exposed in twin parts of the board, leave them exposed to the same number, thus minimizing the amount of combinations that hit.
Rollout
Tom Keith 2013 |
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Match to 17 White 5, Black 16 Black owns 2-cube Black rolls 5-1 1296 games with VR Checker play: 2-ply Cube play: 3-ply Red |
5-1: | Game | G | BG | Equity | ||||
1 | 10/5, 6/5 |
W L |
.5955 .4045 |
.3041 .0911 |
.0643 .0035 | +0.0606 | (b) | |
5 | 16/11, 8/7* |
W L |
.5465 .4535 |
.2608 .1163 |
.0461 .0040 | −0.0726 | (0.1332) | (a) |
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