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Great shootin', Tex -- ROLLOUT and VARIANTS

Posted By: Nack Ballard
Date: Tuesday, 26 March 2019, at 1:35 p.m.

In Response To: Great shootin', Tex -- RO and OTB (Ian Terry)





White is Player 2

score: 0
pip: 157
5 point match
pip: 123
score: 0

Blue is Player 1
XGID=aaBBaBBABA-aaA---bbbbbA-A-:1:1:1:11:0:0:0:5:10
Blue to play 11

1.Rollout124/22 13/12* 12/11* eq: +0.861
Player:
Opponent:		62.27% (G:45.50% B:9.80%)
37.73% (G:7.53% B:0.42%)		Conf.: � 0.009 (+0.852...+0.870) - [94.6%]
Duration: 6 minutes 44 seconds
2.Rollout113/12* 12/11* 5/4*(2) eq: +0.850 (-0.011)
Player:
Opponent:		60.83% (G:46.20% B:10.42%)
39.17% (G:7.26% B:0.37%)		Conf.: � 0.010 (+0.840...+0.860) - [5.4%]
Duration: 6 minutes 18 seconds
3.Rollout213/12* 12/11* 2/1*(2) eq: +0.816 (-0.045)
Player:
Opponent:		60.63% (G:48.65% B:6.68%)
39.37% (G:9.22% B:0.43%)		Conf.: � 0.013 (+0.803...+0.830) - [0.0%]
Duration: 2 minutes 47 seconds
4.Rollout224/22 5/4*(2) eq: +0.795 (-0.066)
Player:
Opponent:		60.35% (G:43.59% B:8.68%)
39.65% (G:8.56% B:0.47%)		Conf.: � 0.012 (+0.784...+0.807) - [0.0%]
Duration: 2 minutes 52 seconds
5.Rollout213/12* 8/7 5/4*(2) eq: +0.729 (-0.132)
Player:
Opponent:		58.04% (G:42.95% B:9.60%)
41.96% (G:8.34% B:0.46%)		Conf.: � 0.014 (+0.716...+0.743) - [0.0%]
Duration: 2 minutes 49 seconds
1 2592 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

2 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

It's funny how reasonable backgammon players can perceive tradeoffs so differently -- even when they arrive at the same play. Others in this thread seem to feel that 24/22 is the important part of the move, whereas I feel thoroughly compelled to hit the two outfield checkers (denying White all spare pips in the outfield) and then think about the other half of the move. It seems to me there's plenty of time to escape the naked five-prime, even if it holds up.

Anyway, Ian's rollout of his original position is shown above. Three variants follow below.






White is Player 2

score: 0
pip: 157
7 point match
pip: 123
score: 0

Blue is Player 1
XGID=aaBBaBBABA-aaA---bbbbbA-A-:1:1:1:11:0:0:0:7:10

Variant 1 (score changed from –5–5 to –7–7)


1.Rollout113/12* 12/11* 5/4*(2) eq: +0.822
Player:
Opponent:		61.11% (G:45.92% B:11.54%)
38.89% (G:6.62% B:0.33%)		Conf.: ± 0.006 (+0.816...+0.828) - [90.2%]
Duration: 21 minutes 36 seconds
2.Rollout124/22 13/12* 12/11* eq: +0.815 (-0.007)
Player:
Opponent:		62.36% (G:45.39% B:13.77%)
37.64% (G:6.91% B:0.47%)		Conf.: ± 0.008 (+0.806...+0.823) - [9.8%]
Duration: 45 minutes 54 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 11856807
Moves: 3-ply, cube decisions: XG Roller

Did anyone mention the relevance of match length? (I didn't read all the posts.) In Variant 1 above, increasing the length of the match from 5 points to 7 is enough to reverse the best play.


Let's further increase the length of the match to essentially "normal score" or unlimited/Money:






White is Player 2

score: 0
pip: 157
Unlimited Game
Jacoby Beaver
pip: 123
score: 0

Blue is Player 1
XGID=aaBBaBBABA-aaA---bbbbbA-A-:1:1:1:11:0:0:3:0:10

Variant 2 (Unlimited/Money)


1.Rollout113/12* 12/11* 5/4*(2) eq: +0.915
Player:
Opponent:		61.30% (G:46.03% B:9.25%)
38.70% (G:6.52% B:0.31%)		Conf.: ± 0.008 (+0.907...+0.924) - [100.0%]
Duration: 15 minutes 40 seconds
2.Rollout124/22 13/12* 12/11* eq: +0.889 (-0.026)
Player:
Opponent:		62.87% (G:45.66% B:7.98%)
37.13% (G:7.18% B:0.37%)		Conf.: ± 0.008 (+0.882...+0.897) - [0.0%]
Duration: 18 minutes 11 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 92798170
Moves: 3-ply, cube decisions: XG Roller

It is worth noting that if the cube is on White's side, B (Both, 24/22 12/11*/10) beats N (Near, 13/12*/11, 5/4*(2)) by .015 (5k rollout, not shown), and that prior to the roll Blue has a correct Money redouble by .046 (1k rollout, not shown).


Finally, let's return the score to –5–5, but nudge forward (1 pip each) Blue's 13pt checker and White's two outfield blots:





White is Player 2

score: 0
pip: 159
5 point match
pip: 122
score: 0

Blue is Player 1
XGID=aaBBaBBABAaaA----bbbbbA-A-:1:1:1:11:0:0:0:5:10

Variant 3 (Alterations: Blue 13/12, White 13/15)


1.Rollout112/11* 11/10* 5/4*(2) eq: +0.897
Player:
Opponent:		61.77% (G:47.24% B:10.50%)
38.23% (G:6.87% B:0.37%)		Conf.: ± 0.007 (+0.891...+0.904) - [100.0%]
Duration: 28 minutes 42 seconds
2.Rollout124/22 12/11* 11/10* eq: +0.870 (-0.027)
Player:
Opponent:		62.34% (G:45.82% B:9.63%)
37.66% (G:7.57% B:0.45%)		Conf.: ± 0.007 (+0.863...+0.877) - [0.0%]
Duration: 34 minutes 45 seconds
3.Rollout212/11* 11/10* 2/1*(2) eq: +0.821 (-0.076)
Player:
Opponent:		60.49% (G:49.09% B:6.92%)
39.51% (G:9.18% B:0.43%)		Conf.: ± 0.013 (+0.808...+0.834) - [0.0%]
Duration: 8 minutes 08 seconds
4.Rollout324/22 5/4*(2) eq: +0.709 (-0.189)
Player:
Opponent:		58.81% (G:43.31% B:12.42%)
41.19% (G:7.75% B:0.50%)		Conf.: ± 0.016 (+0.692...+0.725) - [0.0%]
Duration: 11 minutes 12 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 92798170
Moves: 3-ply, cube decisions: XG Roller

2 1296 Games rolled with Variance Reduction.
Dice Seed: 92798170
Moves: 3-ply, cube decisions: XG Roller

3 1296 Games rolled with Variance Reduction.
Dice Seed: 33595441
Moves: 3-ply, cube decisions: XG Roller


Nice position, Ian!

Nack

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