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OTB & RO

Posted By: John O'Hagan
Date: Thursday, 18 January 2018, at 1:33 a.m.

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

XG recubed me in this position the other day. OTB, I estimated my takepoint at 6.67% like the other commenters. I knew XG would never redouble a mid length race ATS unless I either had a pass or a close take. What's the best tool to figure out whether or not I had a take? If this was a pip vs. pip race (all or almost all checkers from the 4-point out), I'd just plug the raw pip counts into the Kleinman racing formula to get the answer. But this is more of a flat vs. flat bearoff since Blue's average pip count per checker is 4.1 while White's is 4.0. A 41-56 lead in a flat vs. flat bearoff gives the leader a somewhat larger advantage than in a pip vs. pip race. Exactly how much larger, I'm not sure. I decided to use Kleinman to see how large a favorite it would make 41 on roll vs. 56.

The formula is D squared/S where D is the difference between the 2 pip counts and S is their sum. You first subtract 4 from the side on roll before figuring D and S. So that becomes 361/93, a little less than 4. A Kleinman ratio of 4.0 translates to the favorite having 92%. So I would have slightly over 8% in a pip v pip race.

I didn't think my chances would go down from over 8% to less than 6.67% because of the position type, so I took. The RO agrees. It gives me ~7.5%. So a take against an equal or better opponent.





White is Player 2

score: 3
pip: 56
13 point match
pip: 41
score: 10

Blue is Player 1
XGID=--BAAF-------------cccbba-:1:1:1:00:10:3:0:13:10
Blue on roll, cube action?

Analyzed in Rollout No redouble Redouble/Take
Player Winning Chances: 92.47% (G:0.00% B:0.00%) 92.42% (G:0.00% B:0.00%)
Opponent Winning Chances: 7.53% (G:0.00% B:0.00%) 7.58% (G:0.00% B:0.00%)
Cubeless Equities +0.849 +1.244
Cubeful Equities
No redouble:+0.927 (-0.012)±0.001 (+0.926..+0.928)
Redouble/Take:+0.939±0.000 (+0.939..+0.940)
Redouble/Pass:+1.000 (+0.061)
Best Cube action: Redouble / 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: 1 minute 31 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

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