What a great exercise for blitz cubes! The starting point for me is the 52S-55A-F-C reference position, which is a 0.140 pass:
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| XGID=bB-B--C-A---dE---d-e----B-:0:0:1:00:0:0:1:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 67.46% (G:40.12% B:0.57%) | 67.76% (G:41.84% B:0.52%) |
| Opponent Winning Chances: | 32.54% (G:7.42% B:0.38%) | 32.24% (G:7.77% B:0.41%) |
| Cubeless Equities | +0.678 | +1.394 |
| Cubeful Equities | ||
| No double: | +0.853 (-0.147) | ±0.005 (+0.848..+0.859) |
| Double/Take: | +1.140 (+0.140) | ±0.009 (+1.131..+1.149) |
| Double/Pass: | +1.000 | |
| Best Cube action: Double / Pass | ||
| Rollout details | ||
| 5184 Games rolled with Variance Reduction. Dice Seed: 42060932 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 100.0% | |
| Duration: 18 minutes 38 seconds | ||
eXtreme Gammon Version: 2.10
Now, let's analyze the actual positions using some adjustments.
1. An extra checker in the zone for the attacker adds about 0.250 to the equity of the attacker. The defensive 5 point adds about 0.450 to the equity of the defender. So, it looks like those two make our original reference position into a borderline D/ND decision. However, attacker's back checkers are split one pip and, according to Stick, every pip the back checkers of the attacker are split is worth about 0.020. It is that last adjustment that makes the position a small double, I believe.
D/T
2. I haven't studied the effect of the defensive bar point, so I'll just guess it's a small pass.
D/P
3. Likewise, I don't know what effect the defensive four point has on the position, but I'll guesstimate it's about half of that of the five point, so my guess is that it's a small take.
D/T
4. Adding one more pip to the split back checkers compared to #1 adds just a little equity for the attacker, so nothing much changes, still a (more confident now) double and easy take.
D/T
5. Here compared to #2 the situation is quite different; splitting one more pip lets one back checker see the light and it improves our equity significantly. I think it's a sure pass now.
D/P
6. In #3 I guessed a small take, so the extra pip of split might actually make the position into a small pass; in any case the decision must be very close.
D/P