• Mind the match cube!

    From Axel Reichert@21:1/5 to All on Thu Feb 9 07:49:22 2023
    GNU Backgammon Position ID: 2u4PAACtuysAAA
    Match ID : AhlgAQAAIAAE
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+ O: gnubg
    | O O O O O O | | O O | 0 points
    | O O O O | | |
    | O O O | | |
    | | | |
    | | | |
    | |BAR| |^
    | 7 | | |
    | X | | |
    | X X | | |
    | X X X X | | | Cube offered at 8
    | X X X X X | | | 4 points
    +24-23-22-21-20-19------18-17-16-15-14-13-+ X: axel
    Pip counts: O 68, X 73

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  • From MK@21:1/5 to Axel Reichert on Thu Feb 9 01:45:12 2023
    On February 8, 2023 at 11:49:24 PM UTC-7, Axel Reichert wrote:

    GNU Backgammon Position ID: 2u4PAACtuysAAA
    Match ID : AhlgAQAAIAAE

    I very rarely comment on positions and thus I ignore
    almost all posts discussing positions but three out
    of your last consecutive position decision posts being
    about cube vs checker skill did catch my attention to
    say a few words.

    Since even your own experiments demonstrated that
    cube magnifies luck, I can understand wht mentally
    ill gamblers like you would focus more on that. Also
    since it allows more "wiggle room" for bullshit...

    Consider this: in classic backgammon, (i.e. cubeless),
    amatch is a "two out of three" five-pointers, or rarely,
    in the alternative, is a single seven-pointer. Frankly, I'm
    not sure if winning a single seven-pointer is as hard as
    winning two out of three five-pointers and I sure would
    like to see an experiment done on this. But my point is
    that a backgammon world championship can well be
    decided by a two out of three cubeless five-pointers.

    However, since cube promotes luck, a five-pointer or
    even a seven-pointer gamblegammon match wouldn't
    be long enough for luck to even out and skill to emerge.
    Thus, gamblegammon world championships must be
    determined by twentyfive-point matches! Again, I'm not
    sure if winning a single cubeful twentyfive-pointer is as
    hard as winning two out of three five-pointers and I sure
    would like to see an experiment done on this also...!

    One thing that is self evident about the cube's magnifying
    luck is the need for long enough, (i.e. twentyfive-point),
    matches in order for the luck to level out, (and thus the
    only real skill, the "cube skill" skill to emerge out)...!

    My interest in debunking the gamblegammon cube skill
    comes and goes. I drafted an improved Murat mutant
    experiment for you long time ago, that I couldn't gather
    the will to finalize and post here but maybe this will be
    an incentive to finally do it soon...

    MK

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  • From Axel Reichert@21:1/5 to Axel Reichert on Wed Feb 15 09:06:37 2023
    Axel Reichert <mail@axel-reichert.de> writes:

    GNU Backgammon Position ID: 2u4PAACtuysAAA
    Match ID : AhlgAQAAIAAE
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+ O: gnubg
    | O O O O O O | | O O | 0 points
    | O O O O | | |
    | O O O | | |
    | | | |
    | | | |
    | |BAR| |^
    | 7 | | |
    | X | | |
    | X X | | |
    | X X X X | | | Cube offered at 8
    | X X X X X | | | 4 points
    +24-23-22-21-20-19------18-17-16-15-14-13-+ X: axel
    Pip counts: O 68, X 73

    Rollout cubeless equity +0.396 (Money: +0.396)

    Cubeful equities:
    1. Double, pass +1.000
    2. Double, take +1.161 (+0.161)
    3. No double +0.899 (-0.101)
    Proper cube action: Redouble, pass

    Rollout details:
    Player gnubg owns 4-cube:
    0.698 0.000 0.000 - 0.302 0.000 0.000 CL +0.396 CF +0.899
    [0.001 0.000 0.000 - 0.001 0.000 0.000 CL 0.003 CF 0.002]
    Player axel owns 8-cube:
    0.698 0.000 0.000 - 0.302 0.000 0.000 CL +1.161 CF +1.161
    [0.000 0.000 0.000 - 0.000 0.000 0.000 CL 0.000 CF 0.000]
    Truncated cubeful rollout (depth 6) with variance reduction
    36 games, Mersenne Twister dice gen. with seed 449002682 and quasi-random dice Stop when std.errs. are small enough: limit 0.0100 (min. 36 games)
    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
    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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