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501 Essential Backgammon Problems #49 -- Rollout + Variants

Posted By: Igor
Date: Tuesday, 3 September 2013, at 2:32 p.m.

In Response To: 501 Essential Backgammon Problems #49 (Igor)

Robertie remarks that blue has a solid lead in the race and the best way to preserve it is 13/9 10/9. But there are 10 POH rolls for out blot on white's 5pt. Those are costly; time to anchor up.

 White is Player 2 score: 0 pip: 178 Unlimited GameJacoby pip: 160 score: 0 Blue is Player 1
XGID=-b--a-E-C-A-cDb--c-dA---A-:0:0:1:41:0:0:1:0:10
Blue to play 41

1.Rollout124/20 10/9eq: +0.115
 Player:Opponent: 52.06% (G:13.70% B:0.53%)47.94% (G:8.74% B:0.34%) Conf.: ± 0.004 (+0.111...+0.119) - [100.0%]Duration: 4 hours 56 minutes
2.Rollout113/9 10/9eq: +0.102 (-0.013)
 Player:Opponent: 52.35% (G:14.93% B:0.83%)47.65% (G:12.45% B:0.52%) Conf.: ± 0.004 (+0.098...+0.105) - [0.0%]Duration: 4 hours 17 minutes
3.Rollout224/20 6/5eq: +0.055 (-0.060)
 Player:Opponent: 50.45% (G:12.80% B:0.50%)49.55% (G:9.79% B:0.37%) Conf.: ± 0.012 (+0.042...+0.067) - [0.0%]Duration: 28 minutes 07 seconds
1 31104 Games rolled with Variance Reduction.
Dice Seed: 94782038
Moves: 3-ply, cube decisions: XG Roller

2 2592 Games rolled with Variance Reduction.
Dice Seed: 14727302
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

In fact, the 10 POH numbers are so strong for white that 13/9 10/9 does not make it to the top even at DMP:

 White is Player 2 score: 0 pip: 178 1 point match pip: 160 score: 0 Blue is Player 1
XGID=-b--a-E-C-A-cDb--c-dA---A-:0:0:1:41:0:0:0:1:10
Blue to play 41

1.Rollout124/20 10/9eq: +0.038
 Player:Opponent: 51.88% (G:16.40% B:1.78%)48.12% (G:10.31% B:1.00%) Conf.: ± 0.001 (+0.037...+0.039) - [99.7%]Duration: 2 hours 58 minutes
2.Rollout113/9 10/9eq: +0.035 (-0.002)
 Player:Opponent: 51.77% (G:19.55% B:3.05%)48.23% (G:13.54% B:1.65%) Conf.: ± 0.001 (+0.034...+0.037) - [0.3%]Duration: 2 hours 57 minutes
3.Rollout224/20 6/5eq: +0.010 (-0.027)
 Player:Opponent: 50.52% (G:14.28% B:1.86%)49.48% (G:12.59% B:1.26%) Conf.: ± 0.003 (+0.007...+0.014) - [0.0%]Duration: 22 minutes 46 seconds
1 46656 Games rolled with Variance Reduction.
Dice Seed: 94782038
Moves: 3-ply, cube decisions: XG Roller

2 5184 Games rolled with Variance Reduction.
Dice Seed: 14727302
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Naturally, 13/9 10/9 is a blunder at GS:

 White is Player 2 score: 0 pip: 178 2 point match Crawford pip: 160 score: 1 Blue is Player 1
XGID=-b--a-E-C-A-cDb--c-dA---A-:0:0:1:41:1:0:1:2:10
Blue to play 41

1.Rollout124/20 10/9eq: -0.140
 Player:Opponent: 51.24% (G:16.77% B:1.85%)48.76% (G:8.24% B:0.53%) Conf.: ± 0.004 (-0.144...-0.136) - [100.0%]Duration: 18 minutes 11 seconds
2.Rollout124/20 6/5eq: -0.176 (-0.036)
 Player:Opponent: 49.31% (G:14.24% B:1.62%)50.69% (G:8.13% B:0.63%) Conf.: ± 0.004 (-0.180...-0.173) - [0.0%]Duration: 19 minutes 25 seconds
3.Rollout213/9 10/9eq: -0.231 (-0.091)
 Player:Opponent: 52.07% (G:21.10% B:4.46%)47.93% (G:13.62% B:1.26%) Conf.: ± 0.006 (-0.237...-0.225) - [0.0%]Duration: 8 minutes 58 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 28412616
Moves: 3-ply, cube decisions: XG Roller

2 2592 Games rolled with Variance Reduction.
Dice Seed: 28412616
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

And is the right move at GG:

 White is Player 2 score: 1 pip: 178 2 point match Crawford pip: 160 score: 0 Blue is Player 1
XGID=-b--a-E-C-A-cDb--c-dA---A-:0:0:1:41:0:1:1:2:10
Blue to play 41

1.Rollout113/9 10/9eq: +0.324
 Player:Opponent: 53.81% (G:12.41% B:1.52%)46.19% (G:12.19% B:1.24%) Conf.: ± 0.004 (+0.320...+0.329) - [100.0%]Duration: 16 minutes 13 seconds
2.Rollout124/20 10/9eq: +0.306 (-0.019)
 Player:Opponent: 53.28% (G:12.01% B:1.03%)46.72% (G:10.01% B:0.98%) Conf.: ± 0.004 (+0.302...+0.310) - [0.0%]Duration: 16 minutes 40 seconds
3.Rollout224/20 6/5eq: +0.267 (-0.057)
 Player:Opponent: 51.16% (G:12.21% B:1.09%)48.84% (G:13.38% B:1.09%) Conf.: ± 0.004 (+0.263...+0.272) - [0.0%]Duration: 19 minutes 15 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 28412616
Moves: 3-ply, cube decisions: XG Roller

2 5184 Games rolled with Variance Reduction.
Dice Seed: 14727302
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Finally, can we make 13/9 10/9 to be the best move? Sure, just relieve a little pressure on our 20pt blot. It's white's 11pt that makes the difference.

 White is Player 2 score: 0 pip: 182 Unlimited GameJacoby pip: 160 score: 0 Blue is Player 1
XGID=-b--a-E-C-A-eD---c-dA---A-:0:0:1:41:0:0:1:0:10
Blue to play 41

1.Rollout113/9 10/9eq: +0.294
 Player:Opponent: 56.44% (G:16.74% B:0.96%)43.56% (G:10.19% B:0.42%) Conf.: ± 0.008 (+0.285...+0.302) - [100.0%]Duration: 43 minutes 08 seconds
2.Rollout124/20 10/9eq: +0.255 (-0.038)
 Player:Opponent: 55.60% (G:14.87% B:0.64%)44.40% (G:8.38% B:0.34%) Conf.: ± 0.008 (+0.247...+0.263) - [0.0%]Duration: 47 minutes 43 seconds
3.Rollout224/20 6/5eq: +0.153 (-0.140)
 Player:Opponent: 53.42% (G:13.09% B:0.49%)46.58% (G:9.18% B:0.35%) Conf.: ± 0.015 (+0.138...+0.169) - [0.0%]Duration: 13 minutes 22 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 28412616
Moves: 3-ply, cube decisions: XG Roller

2 1296 Games rolled with Variance Reduction.
Dice Seed: 37291974
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

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