Rattlesnake

Robert Zimmerman

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Mar 26, 2023, 11:00:34 PM3/26/23

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XGID=-aa-BCD-----cD---b-db-b-AA:0:0:1:31:0:1:0:7:10

Score is X:0 O:1 7 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O X |
| X O | | O O O |
| X | | O |
| X | | O |
| | X | |
| |BAR| |
| | | |
| | | X |
| O | | X X |
| O | | X X X |
| O | | X X X O O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 148 O: 142 X-O: 0-1/7
Cube: 1
X to play 31

Timothy Chow

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Mar 27, 2023, 9:50:18 AM3/27/23

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When one is deciding whether to split against a three-point board,
it makes a significant difference whether the opponent has 9 checkers
or 10 checkers in the zone. It's usually safe to split against
9 checkers, but risky to split against 10 checkers. Here, the danger
of splitting is mitigated by our own strong board. But still, I would
hit rather than split here. We're not in much danger of getting
primed, and we have decent chances of a successful attack.

---
Tim Chow

Robert Zimmerman

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Mar 28, 2023, 12:42:52 PM3/28/23

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I posted this position not because I expected many to consider it a challenge (present poster excluded), but because it's a nice illustration, I believe, of the power of "the rack" (Robertie), consisting of made 4,5,6 points. See the variant for equities with made 3,5,6 points. The hit still comes out on top, but others come fairly close.

I played 13/10 with the three, thinking X's infield was poorly distributed after the hit.

Bob

XGID=-aa-BCD-----cD---b-db-b-AA:0:0:1:31:0:1:0:7:10

Score is X:0 O:1 7 pt.(s) match.

+24-23-22-21-20-19------18-17-16-15-14-13-+

| X O O O | | O X |
| O O O | | O X |
| O | | X |
| O | | X |

| | X | |
| |BAR| |

| | | |
| X | | |
| X X | | O |
| X X X | | O |

| O O X X X | | O |
+-1--2--3--4--5--6-------7--8--9-10-11-12-+

Pip count X: 148 O: 142 X-O: 0-1/7
Cube: 1
X to play 31

1. Rollout¹ Bar/24 5/2* eq:-0.088
Player: 47.12% (G:18.64% B:0.83%)
Opponent: 52.88% (G:20.22% B:1.98%)
Confidence: ±0.018 (-0.106..-0.070) - [100.0%]

2. Rollout¹ Bar/24 13/10 eq:-0.227 (-0.138)
Player: 44.11% (G:16.02% B:0.62%)
Opponent: 55.89% (G:19.82% B:1.53%)
Confidence: ±0.017 (-0.243..-0.210) - [0.0%]

3. Rollout¹ Bar/21 eq:-0.246 (-0.157)
Player: 44.51% (G:15.59% B:0.91%)
Opponent: 55.49% (G:22.43% B:0.91%)
Confidence: ±0.014 (-0.260..-0.231) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

----------------------------------------------------------------------
VARIANT
----------------------------------------------------------------------
XGID=-aaB-CD-----cD---b-db-b-AA:0:0:1:31:0:1:0:7:10

Score is X:0 O:1 7 pt.(s) match.

+24-23-22-21-20-19------18-17-16-15-14-13-+

| X O O O | | O X |
| O O O | | O X |
| O | | X |
| O | | X |

| | X | |
| |BAR| |

| | | |
| X | | |
| X X | | O |
| X X X | | O |

| O O X X X | | O |
+-1--2--3--4--5--6-------7--8--9-10-11-12-+
Pip count X: 146 O: 142 X-O: 0-1/7

Cube: 1
X to play 31

1. Rollout¹ Bar/24 5/2* eq:-0.296
Player: 42.90% (G:15.87% B:0.67%)
Opponent: 57.10% (G:21.80% B:2.03%)
Confidence: ±0.015 (-0.310..-0.281) - [97.1%]

2. Rollout¹ Bar/24 13/10 eq:-0.317 (-0.021)
Player: 42.29% (G:14.44% B:0.72%)
Opponent: 57.71% (G:20.22% B:1.52%)
Confidence: ±0.016 (-0.333..-0.301) - [2.8%]

3. Rollout¹ Bar/21 eq:-0.329 (-0.033)
Player: 43.03% (G:14.48% B:0.82%)
Opponent: 56.97% (G:24.06% B:0.95%)
Confidence: ±0.014 (-0.343..-0.315) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2