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501 Essential Backgammon Problems #101 -- Rollout + Variant

Posted By: Igor
Date: Thursday, 19 September 2013, at 2:00 a.m.

In Response To: 501 Essential Backgammon Problems #101 (Igor)

The only thing we have in our favor in this priming game is timing. If we manage to contain two white back checkers she would be forced to crunch soon. The best way to block the white back checkers is to make the bar point. The easiest way to make the bar point is to slot it now. We won't be happy if we get hit, but we are not going to win unless we make the bar point before white escapes. Even one escaped checker will provide additional timing to let the other one escape as well. The best move is not even mentioned by Robertie; it might not be obvious that it is best in this position, but at least it is one of the strong candidates to consider.

 White is Player 2 score: 0 pip: 127 Unlimited GameJacoby pip: 154 score: 0 Blue is Player 1
XGID=-b--BBC-A-A-cD-----bbbbbB-:0:0:1:65:0:0:1:0:10
Blue to play 65

1.Rollout113/8 13/7eq: -0.350
 Player:Opponent: 42.64% (G:10.02% B:0.52%)57.36% (G:27.45% B:3.71%) Conf.: ± 0.015 (-0.366...-0.335) - [100.0%]Duration: 27 minutes 31 seconds
2.Rollout113/8 10/4eq: -0.409 (-0.058)
 Player:Opponent: 40.51% (G:11.98% B:0.48%)59.49% (G:21.54% B:1.86%) Conf.: ± 0.011 (-0.420...-0.397) - [0.0%]Duration: 32 minutes 08 seconds
3.Rollout124/13eq: -0.849 (-0.499)
 Player:Opponent: 36.36% (G:8.74% B:0.44%)63.64% (G:37.81% B:1.11%) Conf.: ± 0.014 (-0.863...-0.835) - [0.0%]Duration: 26 minutes 17 seconds
1 1296 Games rolled with Variance Reduction.
Dice Seed: 93968057
Moves: 4-ply, cube decisions: XG Roller+

eXtreme Gammon Version: 2.10

If our timing advantage is reduced, then the safe play becomes a contender. White will have difficult enough time extricating three back checkers. Still, timing is in our favor, so slotting is a tad ahead of the safe play.

 White is Player 2 score: 0 pip: 138 Unlimited GameJacoby pip: 154 score: 0 Blue is Player 1
XGID=-c--BBC-A-A-bD-----bbbbbB-:0:0:1:65:0:0:1:0:10
Blue to play 65

1.Rollout113/8 13/7eq: +0.060
 Player:Opponent: 52.18% (G:16.10% B:1.12%)47.82% (G:23.08% B:3.08%) Conf.: ± 0.003 (+0.056...+0.063) - [100.0%]Duration: 1 hour 41 minutes
2.Rollout113/8 10/4eq: +0.047 (-0.013)
 Player:Opponent: 51.32% (G:18.06% B:1.34%)48.68% (G:18.94% B:1.55%) Conf.: ± 0.004 (+0.043...+0.051) - [0.0%]Duration: 4 hours 11 minutes
3.Rollout224/13eq: -0.165 (-0.225)
 Player:Opponent: 48.57% (G:15.81% B:1.31%)51.43% (G:30.70% B:1.10%) Conf.: ± 0.012 (-0.177...-0.153) - [0.0%]Duration: 23 minutes 35 seconds
1 10368 Games rolled with Variance Reduction.
Dice Seed: 56773318
Moves: 4-ply, cube decisions: XG Roller+

2 1296 Games rolled with Variance Reduction.
Dice Seed: 56773318
Moves: 4-ply, cube decisions: XG Roller+

eXtreme Gammon Version: 2.10

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