On Tuesday, March 7, 2023 at 10:19:15 PM UTC-5, Timothy Chow wrote:
XGID=-Ba-BaC-C---bC---b-cbBb-b-:0:0:1:63:0:0:0:0:10
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O X O O |
| X O | | O O X O O |
| X | | O |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | X |
| O X | | X X X |
| O X | | X O X O X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 133 O: 121 X-O: 0-0
Cube: 1
X to play 63
Hitting twice is obviously the most gammonish play, but XG prefers
the single hit. See the variant, in which O's board is weaker.
1. Rollout¹ 13/7 8/5* eq:-0.014
Player: 47.70% (G:17.57% B:0.41%)
Opponent: 52.30% (G:18.84% B:0.50%)
Confidence: ±0.009 (-0.022..-0.005) - [99.8%]
2. Rollout¹ 13/4 eq:-0.035 (-0.021)
Player: 48.16% (G:12.52% B:0.25%)
Opponent: 51.84% (G:11.69% B:0.37%)
Confidence: ±0.011 (-0.046..-0.024) - [0.2%]
3. Rollout¹ 8/5* 8/2* eq:-0.084 (-0.070)
Player: 46.20% (G:21.80% B:0.34%)
Opponent: 53.80% (G:25.29% B:0.75%)
Confidence: ±0.010 (-0.094..-0.073) - [0.0%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller
eXtreme Gammon Version: 2.19.211.pre-release
-------
Variant
-------
XGID=-Ba-BaC-C---bC---b-cbBc-a-:0:0:1:63:0:0:0:0:10
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O X O O |
| X O | | O O X O |
| X | | O O |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | X |
| O X | | X X X |
| O X | | X O X O X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 133 O: 123 X-O: 0-0
Cube: 1
X to play 63
1. Rollout¹ 8/5* 8/2* eq:+0.249
Player: 54.69% (G:28.65% B:0.60%)
Opponent: 45.31% (G:18.19% B:0.69%)
Confidence: ±0.011 (+0.238..+0.259) - [99.9%]
2. Rollout¹ 13/7 8/5* eq:+0.223 (-0.026)
Player: 54.86% (G:23.97% B:0.71%)
Opponent: 45.14% (G:15.60% B:0.55%)
Confidence: ±0.011 (+0.212..+0.234) - [0.1%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller
eXtreme Gammon Version: 2.19.211.pre-release
---
Tim Chow
Another instance where the double hit works is with the anchor on the 23 instead of the 21. I'm amazed at how often Robertie's BG Opening books inform play past the opening and into the middle game.
He considers the position of the back men, forward anchor/24-point anchor/split, in evaluating a double hit with two blots. The forward anchor in your original position is an argument for limiting risk. You already have a strong position, seems to be his
rationale. And he considers the strength of the opponents board. The stronger the board, the more you want to turn the game around with the double hit.
Sure makes for some subtlety when considering the usual factors for bold/safe play, e.g. playing bold with an advanced anchor and weaker opponent's board.
Bob
XGID=-Ba-BaC-C---bC---b-cb-bBb-:0:0:1:63:0:0:0:0:10
Score is X:0 O:0. Unlimited Game
+24-23-22-21-20-19------18-17-16-15-14-13-+
| O X O O O | | O X |
| O X O O O | | O X |
| O | | X |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | X |
| X X X | | X O |
| X O X O X | | X O |
+-1--2--3--4--5--6-------7--8--9-10-11-12-+
Pip count X: 137 O: 121 X-O: 0-0
Cube: 1
X to play 63
1. Rollout¹ 8/5* 8/2* eq:-0.288
Player: 42.18% (G:18.89% B:0.28%)
Opponent: 57.82% (G:28.67% B:1.89%)
Confidence: ±0.013 (-0.301..-0.275) - [99.1%]
Duration: 2 minutes 51 seconds
2. Rollout¹ 13/7 8/5* eq:-0.309 (-0.021)
Player: 42.24% (G:15.58% B:0.40%)
Opponent: 57.76% (G:23.81% B:1.30%)
Confidence: ±0.011 (-0.320..-0.297) - [0.9%]
Duration: 3 minutes 15 seconds
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