ah_clem, Mike, and Nack all gave simple and logical explanations. When faced by only 7 checkers in the zone we'd rather preserve our racing lead by covering the blot on the 10pt that is subject by quite a few indirect shots from the split white checkers. The more checkers white has in the zone, the more we should be inclined to anchor up. How many does it take? Everybody knows that 10 checkers in the zone pose a serious enough threat to think defense first. While 8 checkers, the same as in the starting position, is still not a force to tip the scales, 9 checkers is the minimum when we should at least start considering choosing the 22pt anchor at the expense of leaving a blot on the 10pt. The last variant illustrates Nack's point regarding split/nonsplit white checkers.
          
 
          
 | | White is Player 2
score: 0
pip: 178 | Unlimited Game
Jacoby Beaver | pip: 163
score: 0
Blue is Player 1 |
|
| XGID=-ba---E-C-A-eD---a-db--AA-:0:0:1:21:0:0:3:0:10 |
| Blue to play 21 |
| 1. | Rollout1 | 13/10 | eq: +0.060 |
| Player:
Opponent: | 51.52% (G:15.31% B:0.88%)
48.48% (G:14.69% B:0.62%) | Conf.: ± 0.006 (+0.055...+0.066) - [100.0%]
Duration: 1 hour 21 minutes |
|
| 2. | Rollout1 | 24/22 23/22 | eq: +0.031 (-0.029) |
| Player:
Opponent: | 50.53% (G:14.52% B:0.77%)
49.47% (G:13.37% B:0.55%) | Conf.: ± 0.006 (+0.025...+0.037) - [0.0%]
Duration: 1 hour 24 minutes |
|
| |
1 10368 Games rolled with Variance Reduction.
Dice Seed: 90614152
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
| | White is Player 2
score: 0
pip: 173 | Unlimited Game
Jacoby Beaver | pip: 163
score: 0
Blue is Player 1 |
|
| XGID=-ba---E-C-A-dD---b-db--AA-:0:0:1:21:0:0:3:0:10 |
| Blue to play 21 |
| 1. | Rollout1 | 13/10 | eq: -0.122 |
| Player:
Opponent: | 47.45% (G:13.03% B:0.73%)
52.55% (G:16.27% B:0.71%) | Conf.: ± 0.017 (-0.138...-0.105) - [100.0%]
Duration: 9 minutes 19 seconds |
|
| 2. | Rollout1 | 24/22 23/22 | eq: -0.173 (-0.051) |
| Player:
Opponent: | 45.68% (G:11.87% B:0.58%)
54.32% (G:14.48% B:0.56%) | Conf.: ± 0.015 (-0.188...-0.157) - [0.0%]
Duration: 9 minutes 44 seconds |
|
| |
1 1296 Games rolled with Variance Reduction.
Dice Seed: 79605209
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
| | White is Player 2
score: 0
pip: 168 | Unlimited Game
Jacoby Beaver | pip: 163
score: 0
Blue is Player 1 |
|
| XGID=-ba---E-C-A-cD---c-db--AA-:0:0:1:21:0:0:3:0:10 |
| Blue to play 21 |
| 1. | Rollout1 | 13/10 | eq: -0.219 |
| Player:
Opponent: | 45.62% (G:12.29% B:0.66%)
54.38% (G:18.64% B:0.78%) | Conf.: ± 0.003 (-0.222...-0.216) - [100.0%]
Duration: 4 hours 59 minutes |
|
| 2. | Rollout1 | 24/22 23/22 | eq: -0.228 (-0.009) |
| Player:
Opponent: | 44.46% (G:11.22% B:0.51%)
55.54% (G:14.91% B:0.62%) | Conf.: ± 0.003 (-0.231...-0.225) - [0.0%]
Duration: 5 hours 36 minutes |
|
| |
1 41472 Games rolled with Variance Reduction.
Dice Seed: 79605209
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
| | White is Player 2
score: 0
pip: 165 | Unlimited Game
Jacoby Beaver | pip: 163
score: 0
Blue is Player 1 |
|
| XGID=-ba---E-C-A-bD-a-c-db--AA-:0:0:1:21:0:0:3:0:10 |
| Blue to play 21 |
| 1. | Rollout1 | 24/22 23/22 | eq: -0.246 |
| Player:
Opponent: | 43.94% (G:11.37% B:0.59%)
56.06% (G:15.66% B:0.64%) | Conf.: ± 0.012 (-0.258...-0.234) - [100.0%]
Duration: 17 minutes 16 seconds |
|
| 2. | Rollout1 | 13/10 | eq: -0.280 (-0.034) |
| Player:
Opponent: | 44.63% (G:12.27% B:0.77%)
55.37% (G:20.05% B:0.91%) | Conf.: ± 0.012 (-0.292...-0.267) - [0.0%]
Duration: 15 minutes 46 seconds |
|
| |
1 2592 Games rolled with Variance Reduction.
Dice Seed: 79605209
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
| | White is Player 2
score: 0
pip: 179 | Unlimited Game
Jacoby Beaver | pip: 163
score: 0
Blue is Player 1 |
|
| XGID=-c----E-C-A-eD---a-db--AA-:0:0:1:21:0:0:3:0:10 |
| Blue to play 21 |
| 1. | Rollout1 | 24/22 23/22 | eq: +0.125 |
| Player:
Opponent: | 52.65% (G:15.94% B:0.95%)
47.35% (G:12.80% B:0.53%) | Conf.: ± 0.006 (+0.119...+0.132) - [100.0%]
Duration: 1 hour 20 minutes |
|
| 2. | Rollout1 | 13/10 | eq: +0.103 (-0.022) |
| Player:
Opponent: | 52.47% (G:16.22% B:1.12%)
47.53% (G:14.42% B:0.59%) | Conf.: ± 0.006 (+0.097...+0.109) - [0.0%]
Duration: 1 hour 19 minutes |
|
| |
1 10368 Games rolled with Variance Reduction.
Dice Seed: 9069776
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10