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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:	+0.530	±0.005 (+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:	+0.557	±0.004 (+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:	+0.624	±0.007 (+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:	+0.503	±0.005 (+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:	+0.553	±0.010 (+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:	+0.581	±0.015 (+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:	+0.562	±0.003 (+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:	+0.643	±0.019 (+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:	+0.683	±0.020 (+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:	+0.719	±0.019 (+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:	+0.707	±0.019 (+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.

Messages In This Thread

• Advanced Backgammon #95
  Igor -- Sunday, 13 April 2014, at 4:10 p.m.
  • Advanced Backgammon #95
    Taper_Mike -- Sunday, 13 April 2014, at 4:54 p.m.
  • Advanced Backgammon #95
    Robert Chow -- Sunday, 13 April 2014, at 6:06 p.m.
  • Advanced Backgammon #95
    Timothy Chow -- Sunday, 13 April 2014, at 6:43 p.m.
  • Sherlock
    Nack Ballard -- Monday, 14 April 2014, at 4:26 a.m.
    • Sherlock
      Stick -- Monday, 14 April 2014, at 5:49 a.m.
    • Sherlock -- solution
      Nack Ballard -- Monday, 14 April 2014, at 7:12 a.m.
      • Sherlock -- solution
        Casper Van der Tak -- Monday, 14 April 2014, at 7:26 a.m.
        • Sherlock -- solution
          Nack Ballard -- Monday, 14 April 2014, at 8:34 a.m.
          • Sherlock -- solution
            Casper Van der Tak -- Monday, 14 April 2014, at 8:45 a.m.
  • Advanced Backgammon #95
    ah_clem -- Monday, 14 April 2014, at 2:01 p.m.
  • Advanced Backgammon #95 -- Rollout and Variants
    Igor -- Tuesday, 15 April 2014, at 11:52 p.m.
    • Advanced Backgammon #95 — 3 More Variants
      Taper_Mike -- Wednesday, 16 April 2014, at 2:35 a.m.
      • Advanced Backgammon #95 — 3 More Variants
        Igor -- Sunday, 27 April 2014, at 4:35 p.m.