• Blotty board

    From Timothy Chow@21:1/5 to All on Wed Jul 27 07:20:27 2022
    XGID=-B--ABDAAb--dB---bBdaa-a--:0:0:1:32:0:0:0:0:10

    X:Player 2 O:Player 1
    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O X | | O O O O |
    | X O X | | O |
    | | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | O | | X |
    | O | | X |
    | O O | | X X X |
    | O O X X | | X X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 117 O: 135 X-O: 0-0
    Cube: 1
    X to play 32

    ---
    Tim Chow

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  • From ah...Clem@21:1/5 to Timothy Chow on Wed Jul 27 14:48:05 2022
    On 7/27/2022 7:20 AM, Timothy Chow wrote:
    XGID=-B--ABDAAb--dB---bBdaa-a--:0:0:1:32:0:0:0:0:10

    X:Player 2   O:Player 1
    Score is X:0 O:0. Unlimited Game  +13-14-15-16-17-18------19-20-21-22-23-24-+
     | X           O  X |   | O  O  O     O    |
     | X           O  X |   | O                |  |                  |   | O                |
     |                  |   | O                |
     |                  |   |                  |
     |                  |BAR|                  |
     |                  |   |                  |
     | O                |   | X                |  | O                |   | X                |  | O        O       |   | X  X           X |
     | O        O  X  X |   | X  X  X        X |  +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count  X: 117  O: 135 X-O: 0-0
    Cube: 1
    X to play 32

    I suppose the idea here is to use the three blots in her home board as
    an excuse to run off the eighteen point. Looks sound. Is it better than
    simply building the board with 8/4 6/3? Not sure.

    If X runs, 61 62 and 63 gives him only one blot to shoot at from the
    bar. The other 12 hitting numbers leave at least two and often three
    homeboard blots after a hit. And if missed X is well poised to easily
    win the race.

    "Don't volunteer a shot in a holding game" is sage advice. Probably
    should be "Don't volunteer a shot in a holding game unless you're almost
    gin if missed and you have lots of counterplay if you are."

    So, I'll pay now with 18/13.

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  • From Timothy Chow@21:1/5 to All on Fri Jul 29 09:24:27 2022
    XGID=-B--ABDAAb--dB---bBdaa-a--:0:0:1:32:0:0:0:0:10

    X:Player 2 O:Player 1
    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O X | | O O O O |
    | X O X | | O |
    | | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | O | | X |
    | O | | X |
    | O O | | X X X |
    | O O X X | | X X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 117 O: 135 X-O: 0-0
    Cube: 1
    X to play 32

    Mainly I wanted to mention that XG 3-ply plays 6/4 6/3 here (although
    if you force a 3-ply evaluation of 18/13, it comes out way ahead of
    6/4 6/3). XG sometimes creates what look to me like unnecessarily
    blotty boards in holding games or mutual holding games, and I have
    always been suspicious of such plays. This position is one small
    piece of evidence that XG (at least at the 3-ply level) may
    underestimate how serious a liability a blotty board is in such
    positions.

    1. Rollout¹ 18/13 eq:+0.464
    Player: 63.25% (G:9.37% B:0.19%)
    Opponent: 36.75% (G:4.89% B:0.20%)
    Confidence: ±0.010 (+0.454..+0.474) - [100.0%]

    2. Rollout¹ 6/4 6/3 eq:+0.333 (-0.131)
    Player: 60.24% (G:8.98% B:0.15%)
    Opponent: 39.76% (G:4.32% B:0.20%)
    Confidence: ±0.010 (+0.323..+0.343) - [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

    ---
    Tim Chow

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