Robertie recommends 24/18 over 13/7 since the latter stands to lose too much ground in the race. However, with three checkers back and stronger board we can afford to play more purely. 13/7 unloads the midpoint and provides both an additional cover for the 5pt and a slot for a potential 4-prime.
         
 
         
 | | White is Player 2
score: 0
pip: 154 | Unlimited Game
Jacoby | pip: 174
score: 0
Blue is Player 1 |
|
| XGID=-a--BAB-C---fD---c-d-a--BA:0:0:1:64:0:0:1:0:10 |
| Blue to play 64 |
| 1. | Rollout1 | Bar/21* 13/7 | eq: +0.144 |
| Player:
Opponent: | 52.90% (G:16.65% B:0.72%)
47.10% (G:12.57% B:0.72%) | Conf.: ± 0.007 (+0.137...+0.151) - [100.0%]
Duration: 1 hour 37 minutes |
|
| 2. | Rollout1 | Bar/21* 24/18 | eq: +0.119 (-0.025) |
| Player:
Opponent: | 52.74% (G:14.65% B:0.71%)
47.26% (G:12.40% B:0.59%) | Conf.: ± 0.006 (+0.113...+0.125) - [0.0%]
Duration: 1 hour 38 minutes |
|
| 3. | Rollout1 | Bar/21* 21/15 | eq: +0.117 (-0.027) |
| Player:
Opponent: | 52.67% (G:15.32% B:0.73%)
47.33% (G:12.82% B:0.75%) | Conf.: ± 0.006 (+0.110...+0.123) - [0.0%]
Duration: 1 hour 34 minutes |
|
| |
1 10368 Games rolled with Variance Reduction.
Dice Seed: 57408517
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
However, if our structure is weakened a bit, e.g., move the 4pt to the 3pt, then the slot indeed becomes too much of a play for too little potential gain.
| | White is Player 2
score: 0
pip: 154 | Unlimited Game
Jacoby | pip: 172
score: 0
Blue is Player 1 |
|
| XGID=-a-B-AB-C---fD---c-d-a--BA:0:0:1:64:0:0:1:0:10 |
| Blue to play 64 |
| 1. | Rollout1 | Bar/21* 24/18 | eq: +0.021 |
| Player:
Opponent: | 50.39% (G:13.94% B:0.63%)
49.61% (G:13.21% B:0.68%) | Conf.: ± 0.004 (+0.017...+0.026) - [99.8%]
Duration: 3 hours 07 minutes |
|
| 2. | Rollout1 | Bar/21* 13/7 | eq: +0.012 (-0.009) |
| Player:
Opponent: | 49.87% (G:15.75% B:0.71%)
50.13% (G:13.91% B:0.91%) | Conf.: ± 0.005 (+0.008...+0.017) - [0.2%]
Duration: 3 hours 08 minutes |
|
| 3. | Rollout1 | Bar/21* 21/15 | eq: +0.010 (-0.011) |
| Player:
Opponent: | 49.96% (G:14.89% B:0.73%)
50.04% (G:13.62% B:0.78%) | Conf.: ± 0.004 (+0.006...+0.015) - [0.0%]
Duration: 3 hours 04 minutes |
|
| |
1 20736 Games rolled with Variance Reduction.
Dice Seed: 94782038
Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.10
I learned from my study of a position from Modern Backgammon that the stronger home board structure makes slotting the bar point go up in value due to a potential priming game in mind.