XGID=aBaBBAB-A----B--Abbdbb-Ba-:1:1:1:41:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X X O O | | O O O X O |
| X O O | | O O O X |
| | | O |
| | | O |
| | | |
| |BAR| |
| | O | |
| | | |
| | | | +---+
| | | X X X X | | 2 |
| X | | X X X X O X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 129 O: 121 X-O: 0-0
Cube: 2, X own cube
X to play 41

---
Tim Chow

XGID=aBaBBAB-A----B--Abbdbb-Ba-:1:1:1:41:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X X O O | | O O O X O |
| X O O | | O O O X |
| | | O |
| | | O |
| | | |
| |BAR| |
| | O | |
| | | |
| | | | +---+
| | | X X X X | | 2 |
| X | | X X X X O X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 129 O: 121 X-O: 0-0
Cube: 2, X own cube
X to play 41

The normal blitzing play in this sort of situation is to switch points
with 6/5 6/2*, and that in fact is what XG 3-ply does. The idea is that
whether you switch points or not, you have a four-point board and a blot
in your board, but if you switch points, the opponent has an extra
checker on the bar. True, you sacrifice your 6pt, but in a blitz, it
usually doesn't matter all that much which points you've made.

However, the rollout below favors 13/8. I think that's because this is
not a "pure" blitzing position. X, after all, is a clear underdog, and
has to escape his two checkers from behind O's five-prime when he's not
even at the edge. A blot on his 2pt is harder to cover than a blot on
the 5pt, and moreover, switching points more or less commits him to a
blitzing plan rather than a priming plan. 13/8 keeps open both options.

For comparison, in the variant, I have scooched up X's back checkers
to the edge of O's prime, and switching points comes out on top.

1. Rollout¹ 13/8 eq:-0.256
Player: 36.68% (G:11.05% B:0.31%)
Opponent: 63.32% (G:21.53% B:1.34%)
Confidence: ±0.010 (-0.266..-0.246) - [100.0%]

2. Rollout¹ 6/5 6/2* eq:-0.322 (-0.066)
Player: 33.83% (G:11.36% B:0.20%)
Opponent: 66.17% (G:20.75% B:1.49%)
Confidence: ±0.010 (-0.333..-0.312) - [0.0%]

3. Rollout¹ 23/22 16/12 eq:-0.329 (-0.073)
Player: 37.43% (G:12.68% B:0.34%)
Opponent: 62.57% (G:30.13% B:3.90%)
Confidence: ±0.012 (-0.341..-0.317) - [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=aBaBBAB-A----B--AbbdbbB-a-:1:1:1:41:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X X O O | | O O O X O |
| X O O | | O O O X |
| | | O |
| | | O |
| | | |
| |BAR| |
| | O | |
| | | |
| | | | +---+
| | | X X X X | | 2 |
| X | | X X X X O X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 127 O: 121 X-O: 0-0
Cube: 2, X own cube
X to play 41

1. Rollout¹ 6/5 6/2* eq:+0.169
Player: 48.45% (G:19.55% B:0.30%)
Opponent: 51.55% (G:15.28% B:0.92%)
Confidence: ±0.011 (+0.158..+0.180) - [100.0%]

2. Rollout¹ 13/8 eq:+0.109 (-0.060)
Player: 47.41% (G:15.49% B:0.35%)
Opponent: 52.59% (G:16.86% B:0.79%)
Confidence: ±0.011 (+0.098..+0.119) - [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

---
Tim Chow