XGID=-a-BB-CbB---bD-B-c-cca----:0:0:1:33:0:1:0:3:10

X:Player 1 O:Player 2

Score is X:0 O:1 3 pt.(s) match.

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

| X X O | | O O O |

| X X O | | O O |

| X O | | O O |

| X | | |

| | | |

| |BAR| |

| | | |

| | | |

| | | X |

| O X O | | X X X |

| O X O | | X X X O |

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

Pip count X: 130 O: 147 X-O: 0-1/3

Cube: 1

X to play 33

Switching points is certainly more gammonish, and typically the trailer in

a match is eager to win a gammon. However, here the cube is centered, and

if X switches points and O dances, then X hugely overshoots his market; if

O enters, X will still double, but his cube won't be particularly efficient.

On the other hand, if X plays 13/10(4), then he has a pretty efficient cube

after almost any response by O.

If X switches points with 4/1*(2), then there's still a question of how to

play the two remaining 2's. If the cube were already turned, then XG says

that 8/5(2) and 13/10(2) are close; however, with the cube centered, XG

strongly prefers 13/10(2) (although it prefers 13/10(4) over either point-

switching play). The magnitude of the difference surprises me, but once

again, the explanation is that the extra 7 dancing rolls afforded by 8/5(2)

don't gain X that much since he overshoots his market.

Among the quiet plays, 13/10(2) 8/5(2) might seem more natural than 13/10(4).

Just make the 5pt, right? However, 13/10(2) 8/5(2) leaves X almost totally

stripped, while 13/10(4) leaves X much more flexible.

For comparison I've rolled out the position for money, where X's upcoming

cube isn't as efficient.

1. Rollout¹ 13/10(4) eq:+0.965

Player: 66.94% (G:12.95% B:0.62%)

Opponent: 33.06% (G:5.27% B:0.30%)

Confidence: ±0.013 (+0.952..+0.977) - [100.0%]

2. Rollout¹ 13/10(2) 4/1*(2) eq:+0.882 (-0.082)

Player: 64.67% (G:18.86% B:0.54%)

Opponent: 35.33% (G:7.93% B:0.46%)

Confidence: ±0.011 (+0.871..+0.894) - [0.0%]

3. Rollout¹ 13/10(2) 8/5(2) eq:+0.826 (-0.138)

Player: 64.14% (G:13.42% B:0.89%)

Opponent: 35.86% (G:6.12% B:0.47%)

Confidence: ±0.013 (+0.814..+0.839) - [0.0%]

4. Rollout¹ 8/5(2) 4/1*(2) eq:+0.777 (-0.188)

Player: 62.65% (G:20.65% B:0.31%)

Opponent: 37.35% (G:7.93% B:0.53%)

Confidence: ±0.010 (+0.767..+0.786) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.

Dice Seed: 271828

Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.207.pre-release, MET: Kazaross XG2

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Money

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XGID=-a-BB-CbB---bD-B-c-cca----:0:0:1:33:0:0:0:0:10

X:Player 1 O:Player 2

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 |

| X X O | | O O |

| X O | | O O |

| X | | |

| | | |

| |BAR| |

| | | |

| | | |

| | | X |

| O X O | | X X X |

| O X O | | X X X O |

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

Pip count X: 130 O: 147 X-O: 0-0

Cube: 1

X to play 33

1. Rollout¹ 13/10(2) 4/1*(2) eq:+0.636

Player: 65.04% (G:19.36% B:0.46%)

Opponent: 34.96% (G:8.41% B:0.33%)

Confidence: ±0.007 (+0.629..+0.644) - [78.0%]

2. Rollout¹ 13/10(4) eq:+0.633 (-0.004)

Player: 66.49% (G:13.45% B:0.42%)

Opponent: 33.51% (G:6.01% B:0.18%)

Confidence: ±0.006 (+0.627..+0.639) - [22.0%]

3. Rollout¹ 8/5(2) 4/1*(2) eq:+0.584 (-0.052)

Player: 62.94% (G:20.64% B:0.40%)

Opponent: 37.06% (G:8.80% B:0.32%)

Confidence: ±0.008 (+0.576..+0.592) - [0.0%]

4. Rollout² 13/10(2) 8/5(2) eq:+0.521 (-0.116)

Player: 64.46% (G:12.49% B:0.39%)

Opponent: 35.54% (G:6.19% B:0.20%)

Confidence: ±0.013 (+0.508..+0.534) - [0.0%]

¹ 5184 Games rolled with Variance Reduction.

Dice Seed: 271828

Moves: 3-ply, cube decisions: XG Roller

² 1296 Games rolled with Variance Reduction.

Dice Seed: 271828

Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.207.pre-release

---

Tim Chow