Smells like quiz factor in here!

White is Player 2

score: 0
pip: 83

Unlimited Game

pip: 167
score: 0

Blue is Player 1

XGID=-BB-B-BA--------acbcbCbBbA:1:-1:1:41:0:0:0:0:10

Blue to play 41

Rollout¹

Bar/21 7/6

eq: -1.003

Player:
Opponent:

29.14% (G:2.19% B:0.05%)
70.86% (G:35.26% B:1.06%)

Conf.: ± 0.004 (-1.007...-0.999) - [100.0%]
Duration: 50 minutes 50 seconds

Rollout¹

Bar/21 6/5

eq: -1.026 (-0.023)

Player:
Opponent:

29.56% (G:2.10% B:0.04%)
70.44% (G:37.28% B:1.31%)

Conf.: ± 0.003 (-1.029...-1.022) - [0.0%]
Duration: 43 minutes 29 seconds

Rollout¹

Bar/21 4/3

eq: -1.041 (-0.038)

Player:
Opponent:

28.21% (G:1.98% B:0.04%)
71.79% (G:38.11% B:1.33%)

Conf.: ± 0.002 (-1.043...-1.038) - [0.0%]
Duration: 44 minutes 13 seconds

¹ 15552 Games rolled with Variance Reduction.
Dice Seed: 39912497
Moves: 3-ply, cube decisions: XG Roller

Rollout by Taper_Mike
2014-Jun-01
eXtreme Gammon Version: 2.10.199.2658
Flashcard PositionID 000910.xgp
n[C E23 e38] "<=15

eXtreme Gammon Version: 2.10

The QF Play Comes Close, but No Cigar

I outlined the advantages of breaking the 6pt in my original post. It turns all 4s except 44 into playable rolls on the next turn. 65 and 64 run. 43 and 42 make the 3pt. 41 makes the 5pt while slotting the 3pt.

The net pickup is on 43, 42, and 41. After playing 7/6 in the original position, if the subsequent roll is 43 or 42, the 6pt is gone, and the 3pt is not gained as recompense. The pickup on 41 is less. After playing 7/6 in the original position, if the subsequent roll is 41, then you kill a checker, but retain the 6pt.

Along with those advantages that come with breaking the 6pt, there are also some disadvantages. First, it will be hard to remake, and there may be shots upcoming. The opponent blots with 44, 55, and 64 on this turn already. Second, 20 times in 36, you will roll the 5 or 6 you need to escape, and you will have sacrificed the 6pt for nothing.

On balance, holding the 6pt is best, but the choice is much closer than I expected it to be. Over the board, I played 7/6 without even considering anything else. Only when the GnuBg Tutor interrupted me, did I stop to analyze what turned out to be an interesting alternative.

Below is the truncated GnuBg rollout that favors breaking the 6pt. It uses settings that mimic XGR++. The margin in the trunc is only 0.001, but in evals using Grandmaster mode, it comes out at 0.01.

Mike

GnuBg Truncated Rollout

No Jacoby, No Beavers

# Ply Move Equity

• 1 R bar/21 6/5 -1.050476

0.286035 0.025374 0.000202 - 0.713965 0.378259 0.013687 -0.794301 -1.050476

0.000835 0.000372 0.000009 - 0.000835 0.001127 0.000204 0.002413 0.002575

Truncated cubeful rollout (depth 5) with var.redn.

360 games, Mersenne Twister dice gen. with seed 715696832 and quasi-random dice

Play: world class 2-ply cubeful prune [world class]

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Skip pruning for 1-ply moves.

Cube: 2-ply cubeful prune [world class]

Different evaluations after 2 plies:

Play: 1-ply cubeful prune

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Cube: 2-ply cubeful prune [world class]

2 R bar/21 7/6 -1.051697 ( -0.001221)

0.278012 0.024471 0.000213 - 0.721988 0.361126 0.011414 -0.791833 -1.051697

0.000946 0.000342 0.000015 - 0.000946 0.001150 0.000149 0.002694 0.003918

Truncated cubeful rollout (depth 5) with var.redn.

360 games, Mersenne Twister dice gen. with seed 715696832 and quasi-random dice

Play: world class 2-ply cubeful prune [world class]

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Skip pruning for 1-ply moves.

Cube: 2-ply cubeful prune [world class]

Different evaluations after 2 plies:

Play: 1-ply cubeful prune

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Cube: 2-ply cubeful prune [world class]

3 R bar/21 4/3 -1.054656 ( -0.004180)

0.276977 0.023216 0.000162 - 0.723023 0.381662 0.013004 -0.817335 -1.054656

0.000900 0.000426 0.000010 - 0.000900 0.001204 0.000186 0.002715 0.002199

Truncated cubeful rollout (depth 5) with var.redn.

360 games, Mersenne Twister dice gen. with seed 715696832 and quasi-random dice

Play: world class 2-ply cubeful prune [world class]

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Skip pruning for 1-ply moves.

Cube: 2-ply cubeful prune [world class]

Different evaluations after 2 plies:

Play: 1-ply cubeful prune

keep the first 0 0-ply moves and up to 8 more moves within equity 0.16

Cube: 2-ply cubeful prune [world class]

Annotation

Truncated Rollout by Taper_Mike
2014-Jun-01
GNU Backgammon 1.02.000-mingw
Flashcard PositionID 000910

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