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501 Essential Backgammon Problems #50 -- Rollouts

Posted By: Igor
Date: Wednesday, 4 September 2013, at 11:43 p.m.

In Response To: 501 Essential Backgammon Problems #50 (Igor)

Robertie suggests not to bother fighting for the 5pt since the play is unlikely to succeed. But there are so many early game positions when you simply must fight for your 5pt even when you are an underdog. This position is one of those.

 White is Player 2 score: 0 pip: 165 Unlimited GameJacoby pip: 138 score: 0 Blue is Player 1
XGID=-a--aaEBD--AcB---cae-----A:0:0:1:51:0:0:1:0:10
Blue to play 51

1.Rollout1Bar/20 6/5* eq: +0.389
 Player:Opponent: 59.28% (G:16.96% B:0.99%)40.72% (G:10.39% B:0.48%) Conf.: ± 0.008 (+0.381...+0.396) - [100.0%]Duration: 29 minutes 47 seconds
2.Rollout1Bar/24 11/6eq: +0.361 (-0.027)
 Player:Opponent: 58.82% (G:16.47% B:0.84%)41.18% (G:9.49% B:0.33%) Conf.: ± 0.009 (+0.352...+0.371) - [0.0%]Duration: 25 minutes 03 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 94782038
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

Now a bonus question: what little changes in the OP would make chose a safer play? I will post the rollout tomorrow so as not to spoil the fun for those who would like to think about it.

Finally, the usual DMP, GS, and GG results.

 White is Player 2 score: 0 pip: 165 1 point match pip: 138 score: 0 Blue is Player 1
XGID=-a--aaEBD--AcB---cae-----A:0:0:1:51:0:0:0:1:10
Blue to play 51

1.Rollout1Bar/20 6/5* eq: +0.170
 Player:Opponent: 58.52% (G:23.29% B:4.09%)41.48% (G:11.63% B:1.42%) Conf.: ± 0.003 (+0.167...+0.173) - [100.0%]Duration: 18 minutes 51 seconds
2.Rollout1Bar/24 11/6eq: +0.150 (-0.020)
 Player:Opponent: 57.52% (G:23.82% B:2.54%)42.48% (G:9.33% B:0.95%) Conf.: ± 0.003 (+0.148...+0.153) - [0.0%]Duration: 15 minutes 03 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 37291974
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

 White is Player 2 score: 0 pip: 165 2 point match Crawford pip: 138 score: 1 Blue is Player 1
XGID=-a--aaEBD--AcB---cae-----A:0:0:1:51:1:0:1:2:10
Blue to play 51

1.Rollout1Bar/20 6/5* eq: -0.043
 Player:Opponent: 58.29% (G:23.56% B:3.92%)41.71% (G:10.42% B:0.97%) Conf.: ± 0.004 (-0.047...-0.039) - [100.0%]Duration: 16 minutes 10 seconds
2.Rollout1Bar/24 11/6eq: -0.057 (-0.015)
 Player:Opponent: 57.86% (G:24.58% B:2.71%)42.14% (G:10.73% B:0.76%) Conf.: ± 0.004 (-0.061...-0.053) - [0.0%]Duration: 13 minutes 13 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 37291974
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

 White is Player 2 score: 1 pip: 165 2 point match Crawford pip: 138 score: 0 Blue is Player 1
XGID=-a--aaEBD--AcB---cae-----A:0:0:1:51:0:1:1:2:10
Blue to play 51

1.Rollout1Bar/20 6/5* eq: +0.518
 Player:Opponent: 60.63% (G:15.24% B:2.45%)39.37% (G:11.21% B:1.53%) Conf.: ± 0.004 (+0.514...+0.521) - [100.0%]Duration: 15 minutes 06 seconds
2.Rollout1Bar/24 11/6eq: +0.464 (-0.053)
 Player:Opponent: 61.00% (G:12.21% B:1.38%)39.00% (G:7.85% B:0.63%) Conf.: ± 0.003 (+0.461...+0.467) - [0.0%]Duration: 12 minutes 39 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 37291974
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

It's NEVER right to choose the weenie play in this position, even at GS.

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