This position came up when I was the on roll player so my decision was what I woud consider the easier of the two. I like this position because it's one that allows many seemingly small details to be altered in one way or another and they have a rather large impact on the position. We can take that knowledge and apply to other similar positions when they come up. First, the original.
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| XGID=--a-bCDBC---bB---ccdA-----:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 73.54% (G:17.34% B:0.48%) | 74.16% (G:17.32% B:0.52%) |
| Opponent Winning Chances: | 26.46% (G:4.07% B:0.16%) | 25.84% (G:4.21% B:0.15%) |
| Cubeless Equities | +0.607 | +1.236 |
| Cubeful Equities | ||
| No double: | +0.866 (-0.134) | ±0.010 (+0.856..+0.876) |
| Double/Take: | +1.041 (+0.041) | ±0.015 (+1.026..+1.056) |
| Double/Pass: | +1.000 | |
| Best Cube action: Double / Pass | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 100.0% | |
| Duration: 4 minutes 52 seconds | ||
eXtreme Gammon Version: 2.10
>So already it's a pass. Why is that? A couple reasons combined. First, the opp's back checker or as Timothy I believe likes to call it the 'rear guard'. This guy is awkwardly placed on the 23pt. By being on the 23pt instead of the 24pt he not only covers less area in our inner board facilitating our plight home but he is moved up into the potential attack zone. Whether it be this turn or 3 turns from now at some point that checker will be put on the bar simply because of its position on the 23pt instead of the natural 24pt. If we shift that checker back here's what we get:
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| XGID=-a--bCDBC---bB---ccdA-----:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 72.07% (G:17.34% B:0.55%) | 72.31% (G:18.14% B:0.66%) |
| Opponent Winning Chances: | 27.93% (G:4.50% B:0.16%) | 27.69% (G:4.76% B:0.19%) |
| Cubeless Equities | +0.574 | +1.169 |
| Cubeful Equities | ||
| No double: | +0.827 (-0.128) | ±0.016 (+0.811..+0.842) |
| Double/Take: | +0.955 | ±0.019 (+0.936..+0.974) |
| Double/Pass: | +1.000 (+0.045) | |
| Best Cube action: Double / Take | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 100.0% | |
| Duration: 5 minutes 38 seconds | ||
eXtreme Gammon Version: 2.10
In some scenarios where the opponent rolls a deuce it will be correct with that blot on the 23pt to pick it up to the 21pt or run it all the way out. This would not be the case were the blot back all the way on the 24pt affording him more coverage.
Now reset the original position and look how easy it is for our back man to escape either by running out in front of a stripped point (midpoint or 21pt anchor) or running completely to safety with some 7s or possibly large doublets. If we make it so that many doesn't so easily find his way home how much will it change the position?
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| XGID=--a-bCDBC---bB---ccd-A----:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 71.76% (G:16.82% B:0.45%) | 72.56% (G:17.01% B:0.43%) |
| Opponent Winning Chances: | 28.24% (G:4.61% B:0.19%) | 27.44% (G:4.67% B:0.20%) |
| Cubeless Equities | +0.560 | +1.154 |
| Cubeful Equities | ||
| No double: | +0.812 (-0.134) | ±0.010 (+0.802..+0.822) |
| Double/Take: | +0.946 | ±0.015 (+0.931..+0.961) |
| Double/Pass: | +1.000 (+0.054) | |
| Best Cube action: Double / Take | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 100.0% | |
| Duration: 5 minutes 34 seconds | ||
eXtreme Gammon Version: 2.10
Already above by moving back one pip we've had a significant impact on the position. We should keep pushing that checker back and see its effect.
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| XGID=--a-bCDBC---bB---ccd--A---:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 70.30% (G:17.19% B:0.46%) | 70.56% (G:17.61% B:0.50%) |
| Opponent Winning Chances: | 29.70% (G:4.83% B:0.18%) | 29.44% (G:5.02% B:0.20%) |
| Cubeless Equities | +0.532 | +1.080 |
| Cubeful Equities | ||
| No double: | +0.784 (-0.067) | ±0.012 (+0.772..+0.796) |
| Double/Take: | +0.851 | ±0.017 (+0.834..+0.868) |
| Double/Pass: | +1.000 (+0.149) | |
| Best Cube action: Double / Take | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 100.0% | |
| Duration: 6 minutes 02 seconds | ||
eXtreme Gammon Version: 2.10
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| XGID=--a-bCDBC---bB---ccd---A--:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 67.23% (G:17.95% B:0.46%) | 67.28% (G:18.22% B:0.53%) |
| Opponent Winning Chances: | 32.77% (G:5.92% B:0.28%) | 32.72% (G:5.82% B:0.27%) |
| Cubeless Equities | +0.467 | +0.944 |
| Cubeful Equities | ||
| No double: | +0.673 (-0.003) | ±0.020 (+0.654..+0.693) |
| Double/Take: | +0.676 | ±0.022 (+0.654..+0.699) |
| Double/Pass: | +1.000 (+0.324) | |
| Best Cube action: Double / Take | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 58.9% | |
| Take Decision confidence: | 100.0% | |
| Duration: 6 minutes 55 seconds | ||
eXtreme Gammon Version: 2.10
Now it has become so hard to escape cleanly over a couple of turns that it's the cube that's in question. Being on the 23pt or 24pt should be roughly the same so I won't bother rolling out the last variation.
A couple more variants worth taking a glance at are below where we move on of our men out of the zone back to the midpoint. This not only affects the race by 7 pips but leaves us a lot less material in the zone to carry out any sort of immediate attack. You see in the breakdown of the numbers the gammons won have dropped significantly. The 7 pips in and of itself I don't believe has a big influence because we're up by so much already that it will not hurt our racing chances much.
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| XGID=--a-bCCBC---bC---ccdA-----:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
eXtreme Gammon Version: 2.10
| Analyzed in Rollout | No double | Double/Take |
| Player Winning Chances: | 73.71% (G:13.12% B:0.31%) | 74.20% (G:14.10% B:0.45%) |
| Opponent Winning Chances: | 26.29% (G:3.93% B:0.13%) | 25.80% (G:4.06% B:0.14%) |
| Cubeless Equities | +0.568 | +1.175 |
| Cubeful Equities | ||
| No double: | +0.852 (-0.139) | ±0.009 (+0.843..+0.861) |
| Double/Take: | +0.991 | ±0.015 (+0.976..+1.006) |
| Double/Pass: | +1.000 (+0.009) | |
| Best Cube action: Double / Take | ||
| Rollout details | ||
| 1296 Games rolled with Variance Reduction. Dice Seed: 98691431 Moves: 3-ply, cube decisions: XG Roller | ||
| Double Decision confidence: | 100.0% | |
| Take Decision confidence: | 89.0% | |
| Duration: 5 minutes 44 seconds | ||
eXtreme Gammon Version: 2.10
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| XGID=--a-bCDBC---bB--bcbcA-----:0:0:1:00:0:0:3:0:10 | |||||
| Blue on roll, cube action? | |||||
| Analyzed in XG Roller++ | No double | Double/Take |
| Player Winning Chances: | 66.73% (G:21.19% B:0.54%) | 67.50% (G:19.86% B:0.46%) |
| Opponent Winning Chances: | 33.27% (G:5.44% B:0.23%) | 32.50% (G:5.23% B:0.21%) |
| Cubeless Equities | +0.495 | +0.998 |
| Cubeful Equities | ||
| No double: | +0.677 (-0.079) | |
| Double/Take: | +0.756 | |
| Double/Pass: | +1.000 (+0.244) | |
| Best Cube action: Double / Take | ||
eXtreme Gammon Version: 2.10
Lastly, when the prime is harder to jump, even though it's an exterior prime which are weak by nature, it means that when we don't escape we get pointed on and contained far more often, will clearly make this an easy take.
Stick