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Posted By: John O'Hagan
Date: Sunday, 10 May 2015, at 3:59 p.m.

In Response To: Bearoff cube action ATS (John O'Hagan)

I passed as Black here. The pass is correct but it is very close. Black needs 15.8% ATS and he wins 15.2%. I came up with EPC's of about 21-23 using Matussek (actuals are 21.4 to 23.2). So White has a little less than a 3 roll position while Black has a little more. We know that a pure 3 roll position would have EPC's of 22-22 and that Black's side would win 21.2%. How to decide if 21-23 gives 23 the required 15.8% or not? I wasn't sure but I figured 21-17 with 21 on roll would be around a pick-em game while 21-21 would give ~80% chances. Each pip in this range would therefore be worth about 7.5% winning chances. The extra 2 pips from 21 to 23 are probably worth less than 7.5% each but they have to be worth a lot less to not bring the win total below 15.8%. So I passed but it is closer than I thought it would be.

Also, this isn't a rolls v rolls position. White has sort of a flat position while Black has a nearly no miss position. White could therefore lose by rolling too many small numbers while Black doesn't get full value out of D2 & D1 and misses with 3 consecutive aces. I would guess that these differences are a net loss for White so EPC's of 21-21 in this kind of bearoff might give the side on roll around 78% chances rather than the 80% I mentioned above. Plus White's actual lead in EPC's is 1.8 pips, not 2.

is Player 2

score: 0
pip: 13
5 point match
pip: 14
score: 0

is Player 1
XGID=-AA--AA---------------cb--:2:1:1:00:0:0:0:5:10
on roll, cube action?

Analyzed in Rollout No redouble Redouble/Take
Player Winning Chances: 84.60% (G:0.00% B:0.00%) 84.60% (G:0.00% B:0.00%)
Opponent Winning Chances: 15.40% (G:0.00% B:0.00%) 15.40% (G:0.00% B:0.00%)
Cubeless Equities +0.692 +1.012
Cubeful Equities
No redouble:+0.850 (-0.150)±0.000 (+0.850..+0.850)
Redouble/Take:+1.012 (+0.012)±0.000 (+1.012..+1.012)
Redouble/Pass:+1.000
Best Cube action: Redouble / Pass
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: 1.3 seconds

eXtreme Gammon Version: 2.00, MET: Kazaross XG2

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