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Midgame cube action - OUTFIELD SYNERGY

Posted By: Nack Ballard
Date: Tuesday, 12 September 2017, at 10:21 p.m.

In Response To: Midgame cube action - RO & VARIANTS (Karol Szczerek)





White is Player 2

score: 0
pip: 132
Unlimited Game
pip: 130
score: 0

Blue is Player 1
XGID=----bCCE-----C-c-c-cb-b--A:0:0:-1:00:0:0:0:0:10

Original Position (Clear double/take)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 68,58% (G:25,36% B:0,29%) 69,03% (G:25,40% B:0,34%)
Opponent Winning Chances: 31,42% (G:4,93% B:0,19%) 30,97% (G:4,97% B:0,20%)
Cubeless Equities +0,577 +1,172
Cubeful Equities
No double:+0,792 (-0,141)±0,008 (+0,784..+0,799)
Double/Take:+0,933±0,012 (+0,922..+0,945)
Double/Pass:+1,000 (+0,067)
Best Cube action: Double / Take
Rollout details
2592 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100,0%
Take Decision confidence:100,0%
Duration: 20 minutes 56 seconds


Above is Karol's rollout of his original (cube action) position. Clear double/take.

In Variant 1 below, a White 7pt spare is back on the midpoint, succumbing to a higher percentage of gammons, and the position is a clear pass:






White is Player 2

score: 0
pip: 138
Unlimited Game
Jacoby Beaver
pip: 130
score: 0

Blue is Player 1
XGID=a--B-BC-C-C-d-----dccB----:0:0:1:00:0:0:3:0:10

Variant 1 (Compared to the original, a White 7pt spare is on her 13pt)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 69.73% (G:27.44% B:0.29%) 69.33% (G:29.58% B:0.36%)
Opponent Winning Chances: 30.27% (G:4.62% B:0.18%) 30.67% (G:5.00% B:0.23%)
Cubeless Equities +0.624 +1.267
Cubeful Equities
No double:+0.820 (-0.180)±0.005 (+0.816..+0.825)
Double/Take:+1.028 (+0.028)±0.008 (+1.020..+1.036)
Double/Pass:+1.000
Best Cube action: Double / Pass
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 29497603
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 14 minutes 52 seconds


Given that White owns her bar point, her 6-pip-away midpoint (regardless of the number of checkers on it) becomes an inefficient outfield point to own. As illustrated in Variant 2 below, if we make White's race 4 pips worse (but with the compensation of greater outfield control), she goes from a clear pass to a borderline take!






White is Player 2

score: 0
pip: 142
Unlimited Game
Jacoby Beaver
pip: 130
score: 0

Blue is Player 1
XGID=a--B-BC-C-Cd------dccB----:0:0:1:00:0:0:3:0:10

Variant 2 (Compared to Variant 1, White owns her 14pt instead of 13pt)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 68.94% (G:30.09% B:0.45%) 67.81% (G:32.05% B:0.51%)
Opponent Winning Chances: 31.06% (G:5.13% B:0.21%) 32.19% (G:5.73% B:0.27%)
Cubeless Equities +0.631 +1.244
Cubeful Equities
No double:+0.816 (-0.174)±0.006 (+0.810..+0.823)
Double/Take:+0.991±0.010 (+0.981..+1.001)
Double/Pass:+1.000 (+0.009)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 29497603
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:96.8%
Duration: 13 minutes 56 seconds


Likewise (compared to Variant 1), if we rob White of 4 pips by moving the four-stack on her 7pt back to her 8pt (improving synergy with her midpoint), she again goes from a clear pass to a borderline take:






White is Player 2

score: 0
pip: 142
Unlimited Game
Jacoby Beaver
pip: 130
score: 0

Blue is Player 1
XGID=a--B-BC-C-C-d----d-ccB----:0:0:1:00:0:0:3:0:10

Variant 3 (Compared to Variant 1, White owns her 8pt instead of 7pt)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 68.79% (G:28.47% B:0.29%) 68.50% (G:30.39% B:0.37%)
Opponent Winning Chances: 31.21% (G:4.85% B:0.20%) 31.50% (G:5.18% B:0.26%)
Cubeless Equities +0.613 +1.246
Cubeful Equities
No double:+0.811 (-0.185)±0.005 (+0.806..+0.817)
Double/Take:+0.997±0.008 (+0.988..+1.005)
Double/Pass:+1.000 (+0.003)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 29497603
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:79.6%
Duration: 13 minutes 36 seconds


If you return to the original position (at the top of this post), try moving back White's five-stack from 7pt to 8pt, or her three-stack from 13pt to 14pt, and compare XGR++ evaluations. Similarly, you'll see that White's equity improves in both cases despite the lost pips.


Finally, going in the other direction, the change in either Variant 4 or Variant 5 below reduces the value of Blue's position to a borderline double.

Nack






White is Player 2

score: 0
pip: 132
Unlimited Game
Jacoby Beaver
pip: 138
score: 0

Blue is Player 1
XGID=a----BCBC-C-c-----eccB----:0:0:1:00:0:0:3:0:10

Variant 4 (Compared to the original, Blue owns his 7pt instead of 3pt)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 67.83% (G:17.23% B:0.36%) 68.11% (G:17.64% B:0.40%)
Opponent Winning Chances: 32.17% (G:5.54% B:0.21%) 31.89% (G:5.64% B:0.24%)
Cubeless Equities +0.475 +0.967
Cubeful Equities
No double:+0.716 (-0.006)±0.006 (+0.710..+0.723)
Double/Take:+0.722±0.009 (+0.713..+0.731)
Double/Pass:+1.000 (+0.278)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 29497603
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:85.2%
Take Decision confidence:100.0%
Duration: 22 minutes 49 seconds
White is Player 2

score: 0
pip: 132
Unlimited Game
Jacoby Beaver
pip: 133
score: 0

Blue is Player 1
XGID=a--B-BC-C--Cc-----eccB----:0:0:1:00:0:0:3:0:10

Variant 5 (Compared to the original, Blue owns his 11pt instead of 10pt)


Analyzed in Rollout No double Double/Take
Player Winning Chances: 65.17% (G:20.21% B:0.24%) 65.21% (G:21.76% B:0.28%)
Opponent Winning Chances: 34.83% (G:4.81% B:0.19%) 34.79% (G:5.07% B:0.22%)
Cubeless Equities +0.458 +0.943
Cubeful Equities
No double:+0.654 (-0.009)±0.006 (+0.648..+0.660)
Double/Take:+0.663±0.008 (+0.655..+0.671)
Double/Pass:+1.000 (+0.337)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 29497603
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:96.3%
Take Decision confidence:100.0%
Duration: 19 minutes 26 seconds

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