• 2-away/7-away checker play

    From Timothy Chow@21:1/5 to All on Fri Feb 10 09:42:41 2023
    XGID=-aa-BCB-D---bAbC-c-ca-b---:0:0:1:44:5:0:0:7:10

    Score is X:5 O:0 7 pt.(s) match.
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O X O | | O O O |
    | O X O | | O O |
    | X O | | O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | X | | |
    | X | | X |
    | O X | | X X X |
    | O X | | X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 125 O: 148 X-O: 5-0/7
    Cube: 1
    X to play 44

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Mon Feb 13 09:21:07 2023
    XGID=-aa-BCB-D---bAbC-c-ca-b---:0:0:1:44:5:0:0:7:10

    Score is X:5 O:0 7 pt.(s) match.
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O X O | | O O O |
    | O X O | | O O |
    | X O | | O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | X | | |
    | X | | X |
    | O X | | X X X |
    | O X | | X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 125 O: 148 X-O: 5-0/7
    Cube: 1
    X to play 44

    This could perhaps be considered an anti-QF postion. The "obvious" play---assuming you see it---is 13/1* 5/1, and indeed that is the
    play that wins the rollout by a mile. Despite the fact that the
    gammon value on a centered cube is elevated when you're leading 2-away/many-away, it's often *not* the right idea to make the
    "gammonish" play. The reason is that a play that wins a lot of
    gammons tends to also lose more gammons. If there's a good chance
    that things will turn around and your opponent will kill your
    gammons by doubling, then all those gammons you were dreaming about
    will vanish into thin air, even if the tables turn in your favor
    again. Your opponent will be eager to turn the cube if she can
    still win a gammon. But here, X is very unlikely to lose a gammon,
    and 13/1* 5/1 wins hugely more (undoubled) gammons.

    All this is obvious, you say? It isn't obvious to XG 3-ply, which
    plays 15/11(3) 13/9.

    1. Rollout¹ 13/1* 5/1 eq:+1.145
    Player: 77.35% (G:37.40% B:1.53%)
    Opponent: 22.65% (G:3.84% B:0.15%)
    Confidence: ±0.014 (+1.131..+1.158) - [100.0%]

    2. Rollout¹ 15/11(3) 13/9 eq:+0.987 (-0.158)
    Player: 80.26% (G:17.73% B:1.15%)
    Opponent: 19.74% (G:1.98% B:0.06%)
    Confidence: ±0.009 (+0.978..+0.996) - [0.0%]

    ¹ 1296 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller

    eXtreme Gammon Version: 2.19.211.pre-release, MET: Kazaross XG2

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)