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RO
Posted By: John O'Hagan
Date: Friday, 3 January 2014, at 5:48 p.m.
In Response To: RO (Mochy)
Mochy asks "But how do you know those % over the board?"
Well you don't know them exactly but you can get pretty close OTB.
You know that your winning chances need to be real close to the trailer's tp in order to have a redouble ATS. His tp is just his MWC if he passes which is ~9%. So we need to have ~90% in order to redouble.
How to estimate White's winning chances OTB? One method is Kleinman's racing formula (D squared/S). This formula is very good for pip v pip races. D squared/S is 144/44 which gives the side on roll about 90% winning chances.
Should we go with that or should we penalize White for having no checkers on the 4point? I wasn't sure so I used Matussek's EPC formula as a guide. It gives EPC's of 25.3 to 34.2, a difference of 8.9 pips. If this is correct then we should penalize Black a pip and do the Kleinman formula for a 2029 pip race. Kleinman gives the side on roll close to 92% chances in such a race.
So it looks like a redouble for White since you're real close (in one direction or the other) to Black's takepoint. Also, I had this position vs. XGR+ (a much better player than I am) so redoubling would have been correct even earlier since it's a no skill position.
Matussek's formula is pretty good at estimating EPC's but I'm not sure I trust the part where it converts EPC's into winning chances. Here's an expalantion of how it works: http://www.bkgm.com/articles/Matussek/BearoffGWC.pdf

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