I found the following position on page 176 of the new Danish backgammon book "Fra basics til badass". Unfortunately, I don't know how to include epc when pasting a position here, but XG says it's 34.0 for blue, and 36.3 for white.
                     |
| ||||
| XGID=-ABD-A-------------aabbaa-:0:0:1:00:0:0:0:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in XG Roller++ | No double | Double/Take |
| Player Winning Chances: | 76,21% (G:0,00% B:0,00%) | 76,21% (G:0,00% B:0,00%) |
| Opponent Winning Chances: | 23,79% (G:0,00% B:0,00%) | 23,79% (G:0,00% B:0,00%) |
| Cubeless Equities | +0,524 | +1,048 |
| Cubeful Equities | ||
| No double: | +0,752 (-0,199) | |
| Double/Take: | +0,951 | |
| Double/Pass: | +1,000 (+0,049) | |
| Best Cube action: Double / Take | ||
eXtreme Gammon Version: 2.10
This makes me ask two questions:
1. Thinking it looked like sort of a rolls position, I found that its epc should be about 33 pips, (7*4+1) + adjustment of 4 pips for an even number of checkers left and a pipcount of 2,75 per checker. I thought "maybe it's because of the 4 point gap", so I tried moving the 5 point checker one pip forward. Now, by the same method, the epc should be 32 pips. However, according to XG, its almost 33. So question: How do I arrive at the epc of 34 for blue?
2. With a leader epc of 34, I would expect the point of last take to be a little less than 2 pips ((34-1)/7-3) if we had a rolls position vs an efficient position, and about 3 pips ((34-7-5)/7) if we had the same leader epc but both players had highly efficient distributions. I would have thought that since both players have rolls-like positions (but with pretty likely misses, of course), the volatility of the position would be at most as high as in a "roll vs efficient" position, and, therefore, that white couldn't take when down over 2 pips. However, he has a small but clear take. Any thoughts on how i could have estimated the point of last take more accurately?