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Previous contact cube provocation plays at BGO.

Posted By: Bob Koca
Date: Thursday, 22 June 2017, at 10:40 p.m.

In Response To: Previous contact cube provocation plays at BGO. (Nack Ballard)

My comment about that first example was "There is probably a Wisecarver paradox position similar to this. Maybe give a checker or two back on the board."

It was a little harder to modify than I thought it would be but I found a likely similar example. It may be surprising how great the equity difference is between the best play which gets cubed and the second best play which does not. I had to push the made 2 point to the one point to make the single blot play fare relatively better and also put 9 checkers on the 3 point making opponent better after either play:

After 18/13, 4/1* it is a small cube and your equity is -.448. After 18/10 doubling is possibly a blunder but your equity of -.826 is lower by a huge amount.

In the original thread I asked where one might have seen the second position but no one responded. It is a misanalyzed problem from Robertie's 501.





White is Player 1

score: 0
pip: 45
Unlimited Game
Jacoby Beaver
pip: 131
score: 0

Blue is Player 2
XGID=aA-IAaa--a--aA-----bbbb-b-:1:-1:-1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No redouble Redouble/Take
Player Winning Chances: 71.57% (G:0.00% B:0.00%) 72.42% (G:0.00% B:0.00%)
Opponent Winning Chances: 28.43% (G:14.27% B:0.26%) 27.58% (G:14.32% B:0.26%)
Cubeless Equities +0.286 +0.605
Cubeful Equities
No redouble:+0.439 (-0.009)±0.003 (+0.435..+0.442)
Redouble/Take:+0.448±0.011 (+0.437..+0.459)
Redouble/Pass:+1.000 (+0.552)
Best Cube action: Redouble / Take
Rollout details
2592 Games rolled with Variance Reduction.
Moves and cube decisions: XG Roller+
Double Decision confidence:94.0%
Take Decision confidence:100.0%
Duration: 5 hours 25 minutes

eXtreme Gammon Version: 2.10





White is Player 1

score: 0
pip: 45
Unlimited Game
Jacoby Beaver
pip: 130
score: 0

Blue is Player 2
XGID=-a-IBaa--aA-a------bbbb-b-:1:-1:-1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No redouble Redouble/Take
Player Winning Chances: 74.51% (G:0.00% B:0.00%) 75.26% (G:0.00% B:0.00%)
Opponent Winning Chances: 25.49% (G:7.41% B:0.36%) 24.74% (G:7.67% B:0.42%)
Cubeless Equities +0.413 +0.849
Cubeful Equities
No redouble:+0.826±0.019 (+0.807..+0.846)
Redouble/Take:+0.719 (-0.108)±0.028 (+0.690..+0.747)
Redouble/Pass:+1.000 (+0.174)
Best Cube action: No redouble / Take
Percentage of wrong pass needed to make the double decision right: 27.7%
Rollout details
165 Games rolled with Variance Reduction.
Moves and cube decisions: XG Roller+
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 27 minutes 36 seconds

eXtreme Gammon Version: 2.10

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