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Backgame variant -- ROLLOUTS

Posted By: Taper_Mike
Date: Tuesday, 3 June 2014, at 11:07 p.m.

In Response To: Backgame variant -- ROLLOUTS (Nack Ballard)

Nack: I think we should add ... 32 and 22 [to the list of swing rolls].

Nice catch. I should have checked all rolls instead of only the 4s.

I am adding Nack’s variants to my flashcard set. I hereby nominate the second of them for Tim Chow’s list of “favorite positions of the year.” In case some readers are wondering how the cube got placed on top in the original position, I am posting the cube decision below.

For those bold enough to replay a 41-move Nactation sequence, here is how I arrived at the OP:

31P-22E-61E-64H-31Z-41D-52Z-32K-53-431-51E-C-41H-42C-21K-2-51H-F-66f̲-3-61H-3-41H-3-52H-53-F-22N-1-62P-32U-63H-32H-55F̲-53Z-54r-64Z-54P-52r-646-41D-53H-41-n

In condensed notation, where, roughly speaking, every second hyphen is omitted, the sequence is:

31P-22E61E-64H31Z-41D52Z-32K53-43151E-C41H42C-21K2-51HF-66f̲3-61H3-41H3-52H53-F22N-162P-32U63H-32H55F̲-53Z54r-64Z54P-52r646-41D53H-41-n

Mike

## Cube Decision

No Jacoby, No Beavers

Blue is on roll. Cube action?
Position ID: 8ObEAQljtoYBDA Match ID: cAkAALAAMAAE

Cube decision
Rollout cubeless equity +0.437638
Cubeful equities:
1.Double, take +0.585074
2.Double, pass +1.000000 +0.414926
3.No double +0.502359 -0.082716
Proper cube action:Double, take
Rollout details
 Win W g W bg Lose L g L bg Cubeless Cubeful Centered 1-cube 0.598862 0.339248 0.013647 - 0.401138 0.107613 0.005368 +0.437638 +0.502359 Standard error 0.000807 0.001333 0.000286 - 0.000807 0.000887 0.000114 0.002291 0.003291 Player GnuBg owns 2-cube 0.599012 0.343168 0.013397 - 0.400988 0.109906 0.005443 +0.878481 +0.585074 Standard error 0.000853 0.001166 0.000265 - 0.000853 0.000844 0.000115 0.004887 0.005746
Truncated cubeful rollout (depth 5) with var.redn.
360 games, Mersenne Twister dice gen. with seed 715854080 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]

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