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Four Rollout Results Posted, Commentary

Posted By: Paul Weaver
Date: Monday, 25 June 2012, at 12:57 p.m.

In Response To: The Man With The $100,000 Breast Plays BG Very Well (Paul Weaver)

First, the cube action before the 61.

		White is Player 2 score: 0 pip: 119 Unlimited Game Jacoby Beaver pip: 121 score: 0 Blue is Player 1
XGID=--aBBCB-B--Ac---B-bdcA-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:	67.70% (G:17.19% B:0.33%)	67.56% (G:19.61% B:0.42%)
Opponent Winning Chances:	32.30% (G:7.63% B:0.22%)	32.44% (G:9.26% B:0.37%)
Cubeless Equities	+0.451	+0.910
Cubeful Equities
No double:	+0.652 (-0.029)	±0.009 (+0.642..+0.661)
Double/Take:	+0.681	±0.013 (+0.668..+0.694)
Double/Pass:	+1.000 (+0.319)
Best Cube action: Double / Take
Rollout details
1296 Games rolled with Variance Reduction. Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:		100.0%
Take Decision confidence:		100.0%
Duration: 21 minutes 08 seconds

eXtreme Gammon Version: 2.03

Second, Blue to play 61 with the cube in the center. With the Jacoby Rule in effect, hitting is way far wrong because of the overkill and very inefficient cube after White's fans (worth about 1.5).

		White is Player 2 score: 0 pip: 119 Unlimited Game Jacoby Beaver pip: 121 score: 0 Blue is Player 1
XGID=--aBBCB-B--Ac---B-bdcA-b--:0:0:1:61:0:0:3:0:10
Blue to play 61

1.	Rollout1	21/15 11/10	eq: +0.554
	Player: Opponent: 64.48% (G:14.36% B:0.45%) 35.52% (G:8.07% B:0.23%) Conf.: ± 0.008 (+0.546...+0.563) - [99.6%] Duration: 26 minutes 00 second
2.	Rollout1	21/15 16/15	eq: +0.538 (-0.016)
	Player: Opponent: 64.39% (G:12.37% B:0.39%) 35.61% (G:8.06% B:0.21%) Conf.: ± 0.008 (+0.530...+0.546) - [0.4%] Duration: 27 minutes 08 seconds
3.	Rollout2	21/15 5/4	eq: +0.513 (-0.041)
	Player: Opponent: 63.24% (G:14.78% B:0.45%) 36.76% (G:9.12% B:0.26%) Conf.: ± 0.013 (+0.499...+0.526) - [0.0%] Duration: 8 minutes 27 seconds
4.	Rollout2	21/14	eq: +0.513 (-0.042)
	Player: Opponent: 63.49% (G:13.33% B:0.44%) 36.51% (G:8.38% B:0.25%) Conf.: ± 0.012 (+0.501...+0.524) - [0.0%] Duration: 9 minutes 08 seconds
5.	Rollout2	11/10 8/2*	eq: +0.393 (-0.161)
	Player: Opponent: 62.32% (G:23.02% B:0.41%) 37.68% (G:15.01% B:0.88%) Conf.: ± 0.009 (+0.385...+0.402) - [0.0%] Duration: 4 minutes 24 seconds
1 3116 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

eXtreme Gammon Version: 2.03

Third, Blue to play 61 if White owns the cube. Blue wins more gammons by hitting, but these are pretty much negated by the additional gammons and backgammon he loses after hitting.

Both 21/15 11/10 and 21/14 leave 14 shots. Why is 21/15 11/10 better? (1) It gives White a suboptimal hit with her 63, forcing her to leave return shots. (2) If White hits the blots in Blue's outfield from the 23pt, Blue gets more return shots after 21/15 11/10 than after 21/14. (3) I am too lazy to add them all up (hope some reader will do it for me), but I suspect that Blue gets more shots on White's non-hitting 5s after 21/5 11/10 than after 21/14.

Before scrolling down, consider how Blue should play 62 instead of 61 in the same position.

		White is Player 2 score: 0 pip: 119 Unlimited Game Jacoby Beaver pip: 121 score: 0 Blue is Player 1
XGID=--aBBCB-B--Ac---B-bdcA-b--:1:-1:1:61:0:0:3:0:10
Blue to play 61

1.	Rollout1	21/15 11/10	eq: +0.229
	Player: Opponent: 64.48% (G:14.87% B:0.43%) 35.52% (G:8.25% B:0.24%) Conf.: ± 0.007 (+0.223...+0.236) - [100.0%] Duration: 4 minutes 10 seconds
2.	Rollout1	11/10 8/2*	eq: +0.193 (-0.037)
	Player: Opponent: 62.33% (G:23.43% B:0.49%) 37.67% (G:15.57% B:1.00%) Conf.: ± 0.008 (+0.185...+0.200) - [0.0%] Duration: 3 minutes 58 seconds
1 1296 Games rolled with Variance Reduction. Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.03

Fourth position. Hitting was wrong by .037 with 61 in the rollout result shown above, but hitting with 62 is tied (and probably best by a hair) in the rollout result shown below. How can hitting be so bad with 61 but so much better with 62?

The best running play with 61, 21/15 11/10, leaves 14 shots. However, the best running play with 62, 21/15 11/9, leaves 16 shots. Running with 21/13 leaves only 15 shots, but it is worse than the 16-shot play, 21/15 11/9. After 21/13, White's 65 (23/12*) is a great shot with few returns, while after 21/15 11/9, White's 63 (13/10*/4) is a lousy shot.

After running 21/15 11/10 with 61, Blue's equity is +.229. After running with 21/15 11/19 with 62, Blue is only +.202. Much better to leave 14 shots than 16.

After hitting with 61 (8/2* 11/10), Blue's equity is .193. After hitting with 62 (8/2* 11/9), Blue's equity is +.204. Blue has more covers and is up one more pip in the race after hitting with 62.

Who would have known? Who would have been able to figure this out over the board? Certainly not I. Run with 61, but maybe hit with 62.

		White is Player 2 score: 0 pip: 119 Unlimited Game Jacoby Beaver pip: 121 score: 0 Blue is Player 1
XGID=--aBBCB-B--Ac---B-bdcA-b--:1:-1:1:62:0:0:3:0:10
Blue to play 62

1.	Rollout1	11/9 8/2*	eq: +0.204
	Player: Opponent: 62.40% (G:24.34% B:0.47%) 37.60% (G:15.69% B:1.09%) Conf.: ± 0.003 (+0.200...+0.207) - [76.0%] Duration: 49 days 17 hours 03 minutes
2.	Rollout1	21/15 11/9	eq: +0.202 (-0.002)
	Player: Opponent: 63.27% (G:15.54% B:0.46%) 36.73% (G:9.10% B:0.31%) Conf.: ± 0.003 (+0.199...+0.205) - [24.0%] Duration: 19.4 seconds
1 10368 Games rolled with Variance Reduction. Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.03

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