No. 11 O'Hagan Cube Problem/Answer

 Red on roll, cube action?  I was Red here against Extreme Gammon XG roller +.  I was on roll down 8-0 to 13.  Could this be a redouble?
 
My OTB estimate is that Blue's basic 4-cube take point ATS is 25% + 2D/3 (D is the difference in scores), around 30.3%.  My OTB estimate for each side's gammon values are 80% + D for the trailer and 20% - 2D (not to go below 6%) for the leader.  So the gammons heavily favor the trailer ATS by around 88% to 6%.
 
So Blue needs ~ 30% plus 88% of my gammons less 6% of his own to take, and he has virtually no recube vig ATS since my 8-cube take point on anything but a last roll position is around 2%.  OTB I estimated my gammon chances at around 10% and his around 25% which changes his take point to approx 37.5%.  Blue's chances are certainly higher than that so the take is clear.
 
Given that Blue has a clear take, do I have enough to redouble?  At scores like this, I've noticed that the trailer's double or redouble is correct if he's within 8% of the oppt's take point and if he has 3 or 4 market losers in 36.  If you have more than 3 or 4 market losers you can double even earlier and you need to be closer to the opponent's take point if you have less than 3-4 market losers.
 
So how often does Red lose his market here?  31 and 11 usually do it, I would think.  Also sequences like 63 or 61 and fan.  Likewise D5 and fan.  How about some normal covering the 5-point number and fan?  It probably depends on how flexible your builder structure is after covering.  Certainly some of these cover + fan sequences lose the market.  So it looks like I have well over 3-4 market losers so I should have a redouble even if I'm not within 8% of his take point.
 
I figured I must be within 10-12% of his 37.5% take point and that I therefore must redouble ATS.  As you can see by the RO result, I underestimated both side's g chances by a little but R/T is still the correct cube action.
 
Using the XG RO numbers, Blue's gammon-adjusted take point is around 41% and he actually wins the game 55% of the time so I'm a full 14% from his take point.  Redoubling is still correct and I think this position is an example of one where you can redouble even when your winning chances are more than  8% away from the oppt's take point since you have more than 3 or 4 market losers in 36.

Rollout below:



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