Rollout

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Rollout

Posted By: Timothy Chow
Date: Tuesday, 10 June 2014, at 12:37 a.m.

In Response To: Another !@*& snake-eyes that I had no clue about (no, that's not nactation) (Timothy Chow)

I thought this one was interesting because I rarely encounter "quiet" positions where the checker play for money and for 4a5a differ. Here, the XG money rollout rather surprisingly favors 8/7(2), volunteering a direct shot when ahead in the race. At 4a5a, 11/9 comes out on top, followed by 24/22.
This sort of discrepancy can often be explained by the imminent cube action. The position is gammonish enough that Blue is noticeably more eager to cube at 4a5a than for money. For example, after 11/9, suppose White rolls 44, making her 4pt. Then the computer still clearly favors an immediate double at 4a5a, but hesitates for money. Given this, it would make sense that the computer would be more hesitant at 4a5a to leave a direct shot and risk losing the double by playing 8/7(2). However, it's still not clear to me why 8/7(2) is favored for money. Next turn, Blue still usually wants to cube for money, so why allow a direct shot? Perhaps XG Roller is screwing up the subsequent cube action?
Grant favored 8/7(2) for money (while still favoring 11/9 ATS) so I'm still hoping he can elaborate on his reasons.

White is Player 2

score: 2
pip: 154

7 point match

pip: 143
score: 3

Blue is Player 1

XGID=-aa-B-D-C--AdD---bad-b--A-:0:0:1:11:3:2:0:7:10
Blue to play 11

1. Rollout¹ 11/9 6/5(2) eq: +0.748
Player:
Opponent: 64.29% (G:20.58% B:2.47%)
35.71% (G:9.69% B:0.48%) Conf.: ą 0.009 (+0.739...+0.757) - [100.0%]
Duration: 1 hour 12 minutes
2. Rollout¹ 24/22 6/5(2) eq: +0.710 (-0.038)
Player:
Opponent: 64.07% (G:18.70% B:2.25%)
35.93% (G:9.81% B:0.54%) Conf.: ą 0.009 (+0.702...+0.719) - [0.0%]
Duration: 1 hour 12 minutes
3. Rollout¹ 8/7(2) 6/5(2) eq: +0.686 (-0.063)
Player:
Opponent: 64.50% (G:20.94% B:1.75%)
35.50% (G:10.64% B:0.57%) Conf.: ą 0.007 (+0.678...+0.693) - [0.0%]
Duration: 58 minutes 02 seconds
4. Rollout¹ 8/5 6/5 eq: +0.668 (-0.081)
Player:
Opponent: 62.78% (G:21.46% B:2.17%)
37.22% (G:10.32% B:0.60%) Conf.: ą 0.009 (+0.659...+0.677) - [0.0%]
Duration: 1 hour 06 minutes

¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

For money:

White is Player 2

score: 0
pip: 154

Unlimited Game

pip: 143
score: 0

Blue is Player 1

XGID=-aa-B-D-C--AdD---bad-b--A-:0:0:1:11:0:0:0:0:10
Blue to play 11

1. Rollout¹ 8/7(2) 6/5(2) eq: +0.622
Player:
Opponent: 64.62% (G:20.78% B:1.08%)
35.38% (G:10.65% B:0.47%) Conf.: ą 0.006 (+0.616...+0.629) - [100.0%]
Duration: 1 hour 03 minutes
2. Rollout¹ 11/9 6/5(2) eq: +0.599 (-0.023)
Player:
Opponent: 64.29% (G:20.42% B:1.11%)
35.71% (G:9.64% B:0.34%) Conf.: ą 0.008 (+0.591...+0.607) - [0.0%]
Duration: 1 hour 17 minutes
3. Rollout² 24/22 6/5(2) eq: +0.566 (-0.056)
Player:
Opponent: 63.87% (G:18.78% B:1.06%)
36.13% (G:9.93% B:0.35%) Conf.: ą 0.014 (+0.552...+0.580) - [0.0%]
Duration: 21 minutes 20 seconds
4. Rollout² 8/5 6/5 eq: +0.563 (-0.059)
Player:
Opponent: 62.98% (G:21.15% B:1.04%)
37.02% (G:10.21% B:0.36%) Conf.: ą 0.015 (+0.548...+0.578) - [0.0%]
Duration: 19 minutes 24 seconds

¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

² 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10