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Tricky pair of Variants, and Rollouts

Posted By: Nack Ballard
Date: Sunday, 14 September 2025, at 8:27 p.m.

In Response To: A tricky one or ... Rollout (pierrez)





White is Joueur 2

score: 0
pip: 92
Unlimited Game
Jacoby Beaver
pip: 111
score: 0

Blue is Joueur 1
XGID=-BB-ACB-A---bB--bb-bBcaba-:0:0:1:64:0:0:3:0:10
White Spare is on 4pt

1.Rollout113/7 8/4eq: -0,544
Player:
Opponent:		34,03% (G:3,66% B:0,11%)
65,97% (G:3,16% B:0,05%)		Conf.: ± 0,008 (-0,552...-0,536) - [53,6%]
Duration: 9 minutes 51 seconds
2.Rollout120/14 8/4eq: -0,545 (-0,001)
Player:
Opponent:		33,47% (G:4,43% B:0,09%)
66,53% (G:5,92% B:0,06%)		Conf.: ± 0,008 (-0,553...-0,537) - [45,1%]
Duration: 8 minutes 57 seconds
3.Rollout120/10eq: -0,556 (-0,011)
Player:
Opponent:		32,97% (G:5,22% B:0,10%)
67,03% (G:7,83% B:0,14%)		Conf.: ± 0,010 (-0,565...-0,546) - [1,2%]
Duration: 6 minutes 55 seconds
4.Rollout113/3eq: -0,578 (-0,034)
Player:
Opponent:		32,92% (G:5,93% B:0,28%)
67,08% (G:5,63% B:0,27%)		Conf.: ± 0,008 (-0,586...-0,570) - [0,0%]
Duration: 7 minutes 39 seconds
5.4-ply13/9 13/7eq: -0,567 (-0,023)
Player:
Opponent:		31,66% (G:2,01% B:0,02%)
68,34% (G:2,85% B:0,23%)
1 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.211.pre-release

Pierrez posted a very interesting position and followed up with the rollout above.

Note the location of White's spare on the 4pt. Let's see what happens when that spare is

(a) moved back to the 8pt; or
(b) moved forward to the 2pt.

Rollouts of these variants are posted below. In both cases, C (out-and-cover) is better than O (down-and-cover). Notably, the best play of D (Down, 13/9 13/7) in one position is a whopper in the other position!

Nack





White is Player 2

score: 0
pip: 96
Unlimited Game
Jacoby Beaver
pip: 111
score: 0

Blue is Player 1
XGID=-BB-ACB-A---bB--bc-bBbaba-:0:0:1:64:0:0:3:0:10
White Spare is on 8pt


1.Rollout113/9 13/7eq: -0.478
Player:
Opponent:		35.83% (G:2.81% B:0.05%)
64.17% (G:3.14% B:0.23%)		Conf.: ± 0.006 (-0.484...-0.472) - [100.0%]
Duration: 9 minutes 47 seconds
2.Rollout120/14 8/4eq: -0.507 (-0.028)
Player:
Opponent:		33.93% (G:3.78% B:0.07%)
66.07% (G:6.87% B:0.07%)		Conf.: ± 0.007 (-0.514...-0.499) - [0.0%]
Duration: 7 minutes 05 seconds
3.Rollout120/10eq: -0.508 (-0.030)
Player:
Opponent:		33.76% (G:4.30% B:0.06%)
66.24% (G:7.32% B:0.12%)		Conf.: ± 0.007 (-0.515...-0.501) - [0.0%]
Duration: 7 minutes 00 second
4.Rollout113/7 8/4eq: -0.518 (-0.040)
Player:
Opponent:		34.81% (G:3.02% B:0.06%)
65.19% (G:2.45% B:0.05%)		Conf.: ± 0.006 (-0.524...-0.512) - [0.0%]
Duration: 8 minutes 08 seconds
5.Rollout113/3eq: -0.532 (-0.054)
Player:
Opponent:		34.36% (G:3.75% B:0.13%)
65.64% (G:3.61% B:0.16%)		Conf.: ± 0.006 (-0.538...-0.527) - [0.0%]
Duration: 7 minutes 02 seconds
1 2592 Games rolled with Variance Reduction.
Dice Seed: 66195124
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10
White is Player 2

score: 0
pip: 90
Unlimited Game
Jacoby Beaver
pip: 111
score: 0

Blue is Player 1
XGID=-BB-ACB-A---bB--bb-bBbaca-:0:0:1:64:0:0:3:0:10
White Spare is on 2pt


1.Rollout120/14 8/4eq: -0.541
Player:
Opponent:		33.94% (G:4.60% B:0.09%)
66.06% (G:5.59% B:0.06%)		Conf.: ± 0.003 (-0.544...-0.538) - [100.0%]
Duration: 15 minutes 40 seconds
2.Rollout113/7 8/4eq: -0.554 (-0.013)
Player:
Opponent:		33.87% (G:3.29% B:0.08%)
66.13% (G:3.11% B:0.06%)		Conf.: ± 0.003 (-0.558...-0.551) - [0.0%]
Duration: 17 minutes 50 seconds
3.Rollout120/10eq: -0.558 (-0.017)
Player:
Opponent:		33.34% (G:4.98% B:0.08%)
66.66% (G:6.38% B:0.13%)		Conf.: ± 0.003 (-0.561...-0.555) - [0.0%]
Duration: 13 minutes 20 seconds
4.Rollout213/3eq: -0.584 (-0.043)
Player:
Opponent:		33.10% (G:4.83% B:0.27%)
66.90% (G:5.06% B:0.28%)		Conf.: ± 0.005 (-0.589...-0.579) - [0.0%]
Duration: 4 minutes 53 seconds
5.Rollout313/9 13/7eq: -0.641 (-0.100)
Player:
Opponent:		31.48% (G:2.51% B:0.05%)
68.52% (G:3.00% B:0.23%)		Conf.: ± 0.008 (-0.649...-0.633) - [0.0%]
Duration: 4 minutes 31 seconds
1 7776 Games rolled with Variance Reduction.
Dice Seed: 73402750
Moves: 3-ply, cube decisions: XG Roller

2 2592 Games rolled with Variance Reduction.
Dice Seed: 73402750
Moves: 3-ply, cube decisions: XG Roller

3 1296 Games rolled with Variance Reduction.
Dice Seed: 73402750
Moves: 3-ply, cube decisions: XG Roller

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