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Advanced Backgammon #95 -- Rollout and Variants

Posted By: Igor
Date: Tuesday, 15 April 2014, at 11:52 p.m.

In Response To: Advanced Backgammon #95 (Igor)

First off, such early blitz positions are best handled by knowing standard reference positions and then adjusting. This is exactly what Tim and Nack did. A similar standard reference position is 51S-55A-F-C or, equivalently, 52S-55A-2-C, which is a medium no double:





White is Player 2

score: 0
pip: 162
Unlimited Game
Jacoby
pip: 147
score: 0

Blue is Player 1
XGID=aBaB--C-A---dE---d-e----B-:0:0:1:00:0:0:1:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 60.08% (G:29.05% B:0.57%) 60.26% (G:29.62% B:0.55%)
Opponent Winning Chances: 39.92% (G:10.08% B:0.50%) 39.74% (G:10.27% B:0.50%)
Cubeless Equities +0.392 +0.798
Cubeful Equities
No double:+0.5300.005 (+0.525..+0.535)
Double/Take:+0.484 (-0.046)0.007 (+0.477..+0.491)
Double/Pass:+1.000 (+0.470)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 8.2%
Rollout details
10368 Games rolled with Variance Reduction.
Dice Seed: 42060932
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 54 minutes 50 seconds

Rollout by Igor Erovenko
2013-Mar-03
eXtreme Gammon Version: 2.10
52S-55A-2-C-ie.xgp
52S-55A-2-C [N 530-46] "<=10

eXtreme Gammon Version: 2.10

By the way, for those who are yet to start learning early blitz references, the above position plus the next two can go a long way:





White is Player 2

score: 0
pip: 160
Unlimited Game
Jacoby
pip: 147
score: 0

Blue is Player 1
XGID=aB-Ba-C-A---dE---d-e----B-:0:0:1:00:0:0:1:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 60.75% (G:30.22% B:0.51%) 60.90% (G:30.75% B:0.48%)
Opponent Winning Chances: 39.25% (G:9.69% B:0.48%) 39.10% (G:9.84% B:0.49%)
Cubeless Equities +0.421 +0.854
Cubeful Equities
No double:+0.5570.004 (+0.554..+0.561)
Double/Take:+0.546 (-0.011)0.005 (+0.541..+0.551)
Double/Pass:+1.000 (+0.443)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 2.5%
Rollout details
20736 Games rolled with Variance Reduction.
Dice Seed: 48255426
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 1 hour 47 minutes

Rollout by Igor Erovenko
2013-Mar-03
eXtreme Gammon Version: 2.10
52S-55A-4-C-ie.xgp
52S-55A-4-C [N 557-11] "<=20

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 159
Unlimited Game
Jacoby
pip: 147
score: 0

Blue is Player 1
XGID=aB-B-aC-A---dE---d-e----B-:0:0:1:00:0:0:1:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 61.57% (G:31.05% B:0.50%) 61.90% (G:32.01% B:0.48%)
Opponent Winning Chances: 38.43% (G:9.23% B:0.45%) 38.10% (G:9.53% B:0.48%)
Cubeless Equities +0.450 +0.925
Cubeful Equities
No double:+0.592 (-0.033)0.005 (+0.587..+0.597)
Double/Take:+0.6240.007 (+0.617..+0.632)
Double/Pass:+1.000 (+0.376)
Best Cube action: Double / Take
Rollout details
10368 Games rolled with Variance Reduction.
Dice Seed: 48255426
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 50 minutes 33 seconds

Rollout by Igor Erovenko
2013-Mar-03
eXtreme Gammon Version: 2.10
52S-55A-5-C-ie.xgp
52S-55A-5-C [D 624-33] "<=10

eXtreme Gammon Version: 2.10

Now, back to the OP. Both Tim and Nack pointed out their adjustments compared to the reference position. I don't have much to add to those comments. An extra checker in the zone for blue is huge; a checker off the bar for white is also huge, but minus a checker off her 8pt is somewhat bad. Therefore, the OP is a bit worse for white as compared to the reference position, but not as much as to make it a double.





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 145
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---c-e----B-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 59.34% (G:30.03% B:0.52%) 59.63% (G:30.90% B:0.52%)
Opponent Winning Chances: 40.66% (G:9.58% B:0.51%) 40.37% (G:9.72% B:0.52%)
Cubeless Equities +0.391 +0.809
Cubeful Equities
No double:+0.5030.005 (+0.498..+0.508)
Double/Take:+0.483 (-0.020)0.007 (+0.475..+0.490)
Double/Pass:+1.000 (+0.497)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 3.8%
Rollout details
10368 Games rolled with Variance Reduction.
Dice Seed: 4958704
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 58 minutes 53 seconds

eXtreme Gammon Version: 2.10

Now to the variants similar to the reference positions. There should be no surprises in the rollout results.





White is Player 2

score: 0
pip: 155
Unlimited Game
Jacoby Beaver
pip: 145
score: 0

Blue is Player 1
XGID=-B-Ba-C-A-aAeD---c-e----B-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 60.28% (G:30.70% B:0.50%) 60.58% (G:31.86% B:0.50%)
Opponent Winning Chances: 39.72% (G:9.16% B:0.49%) 39.42% (G:9.32% B:0.52%)
Cubeless Equities +0.421 +0.874
Cubeful Equities
No double:+0.513 (-0.040)0.006 (+0.507..+0.519)
Double/Take:+0.5530.010 (+0.543..+0.564)
Double/Pass:+1.000 (+0.447)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 46610111
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 27 minutes 52 seconds

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 154
Unlimited Game
Jacoby Beaver
pip: 145
score: 0

Blue is Player 1
XGID=-B-B-aC-A-aAeD---c-e----B-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 60.44% (G:30.77% B:0.47%) 60.76% (G:31.81% B:0.48%)
Opponent Winning Chances: 39.56% (G:8.47% B:0.47%) 39.24% (G:8.63% B:0.48%)
Cubeless Equities +0.432 +0.894
Cubeful Equities
No double:+0.513 (-0.068)0.009 (+0.505..+0.522)
Double/Take:+0.5810.015 (+0.566..+0.596)
Double/Pass:+1.000 (+0.419)
Best Cube action: Double / Take
Rollout details
2592 Games rolled with Variance Reduction.
Dice Seed: 46610111
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 13 minutes 56 seconds

eXtreme Gammon Version: 2.10

Finally, it is a good opportunity to test Stick's ballpark estimate that every point the back checkers are split is worth .020.





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 144
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---c-e---AA-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 60.54% (G:30.91% B:0.50%) 60.80% (G:31.68% B:0.50%)
Opponent Winning Chances: 39.46% (G:9.33% B:0.49%) 39.20% (G:9.49% B:0.51%)
Cubeless Equities +0.427 +0.876
Cubeful Equities
No double:+0.555 (-0.007)0.002 (+0.553..+0.557)
Double/Take:+0.5620.003 (+0.559..+0.565)
Double/Pass:+1.000 (+0.438)
Best Cube action: Double / Take
Rollout details
46656 Games rolled with Variance Reduction.
Dice Seed: 68015277
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 4 hours 21 minutes

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 143
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---c-e--A-A-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 61.59% (G:31.94% B:0.53%) 61.83% (G:32.89% B:0.54%)
Opponent Winning Chances: 38.41% (G:8.99% B:0.46%) 38.17% (G:9.12% B:0.50%)
Cubeless Equities +0.462 +0.949
Cubeful Equities
No double:+0.583 (-0.060)0.016 (+0.567..+0.599)
Double/Take:+0.6430.019 (+0.624..+0.662)
Double/Pass:+1.000 (+0.357)
Best Cube action: Double / Take
Rollout details
1296 Games rolled with Variance Reduction.
Dice Seed: 68015277
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 7 minutes 17 seconds

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 142
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---c-e-A--A-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 61.93% (G:32.01% B:0.55%) 62.37% (G:32.82% B:0.56%)
Opponent Winning Chances: 38.07% (G:8.99% B:0.47%) 37.63% (G:9.15% B:0.49%)
Cubeless Equities +0.470 +0.970
Cubeful Equities
No double:+0.604 (-0.079)0.014 (+0.590..+0.617)
Double/Take:+0.6830.020 (+0.664..+0.703)
Double/Pass:+1.000 (+0.317)
Best Cube action: Double / Take
Rollout details
1296 Games rolled with Variance Reduction.
Dice Seed: 68015277
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 6 minutes 45 seconds

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 141
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---c-eA---A-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 62.82% (G:31.36% B:0.49%) 63.26% (G:31.95% B:0.50%)
Opponent Winning Chances: 37.18% (G:7.80% B:0.37%) 36.74% (G:7.82% B:0.36%)
Cubeless Equities +0.493 +1.016
Cubeful Equities
No double:+0.628 (-0.091)0.012 (+0.616..+0.641)
Double/Take:+0.7190.019 (+0.700..+0.737)
Double/Pass:+1.000 (+0.281)
Best Cube action: Double / Take
Rollout details
1296 Games rolled with Variance Reduction.
Dice Seed: 68015277
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 7 minutes 06 seconds

eXtreme Gammon Version: 2.10





White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 139
score: 0

Blue is Player 1
XGID=-BaB--C-A-aAeD---cAe----A-:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 63.21% (G:30.69% B:0.53%) 63.35% (G:31.27% B:0.52%)
Opponent Winning Chances: 36.79% (G:8.43% B:0.38%) 36.65% (G:8.49% B:0.40%)
Cubeless Equities +0.488 +0.992
Cubeful Equities
No double:+0.635 (-0.072)0.014 (+0.621..+0.648)
Double/Take:+0.7070.019 (+0.688..+0.725)
Double/Pass:+1.000 (+0.293)
Best Cube action: Double / Take
Rollout details
1296 Games rolled with Variance Reduction.
Dice Seed: 83750779
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 6 minutes 51 seconds

eXtreme Gammon Version: 2.10

I'd say not bad.

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