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Rollout

Posted By: John O'Hagan
Date: Wednesday, 4 September 2013, at 1:39 a.m.

In Response To: Cube action ATS? (John O'Hagan)

I had this position vs. XGR+ the other day and doubled. The RO shows that cubing is a blunder. The trailer's dead cube tp ats is 35%, the g values favor the trailer by approximately 100%/50%, and the leader's 4-cube tp is 40%. Plugging in each sides gammon chances (per the RO) makes the gammon-adjusted tp ~40%. Cube vig, assuming 70% efficiency on the recube, should be worth about 11% which makes the true tp around 29%.

So the leader is within 3% or so of the trailer's true takepoint which is usually close enough to offer an initial cube. Not here though. Here doubling is a blunder. BG is a tough game.

By the way, an easier (but somewhat less accurate) way to estimate the trailer's tp ats is to figure out what it would be if the trailer auto recubes on his next shake then subtract 2% - 3% to get the true tp. Here that gives you 33% less 2% or 3%. This is a good method to use when you don't have much confidence in your gammon chance estimates since g's are irrelevant when the cube is on 4 and both sides are 4a or less from winning the match.

 is Player 2 score: 0 pip: 152 4 point match pip: 143 score: 1 is Player 1
XGID=-bBB-BB----AcD---d-e--a-B-:0:0:1:00:1:0:0:4:10
on roll, cube action?

 Analyzed in Rollout No double Double/Take Player Winning Chances: 67.48% (G:27.07% B:3.89%) 66.60% (G:28.24% B:8.41%) Opponent Winning Chances: 32.52% (G:7.60% B:0.56%) 33.40% (G:7.90% B:0.50%) Cubeless Equities +0.803 +1.335 Cubeful Equities No double: +0.732 ±0.019 (+0.714..+0.751) Double/Take: +0.614 (-0.119) ±0.028 (+0.586..+0.641) Double/Pass: +1.000 (+0.268) Best Cube action: No double / Take Percentage of wrong pass needed to make the double decision right: 23.5% 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: 43 minutes 22 seconds

eXtreme Gammon Version: 2.00, MET: Kazaross XG2

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