• Hit or play safe? 2

    From Timothy Chow@21:1/5 to All on Fri Mar 24 09:19:48 2023
    XGID=--aB--DaB---bD---b-e-bB-bA:0:0:1:21:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O X O |
    | X O | | O O X O |
    | X | | O |
    | X | | O |
    | | X | O |
    | |BAR| |
    | | | |
    | | | X |
    | | | X |
    | O X | | X X |
    | O X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 167 O: 123 X-O: 0-0
    Cube: 1
    X to play 21

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Robert Zimmerman@21:1/5 to Timothy Chow on Fri Mar 24 10:07:13 2023
    On Friday, March 24, 2023 at 9:19:50 AM UTC-4, Timothy Chow wrote:
    XGID=--aB--DaB---bD---b-e-bB-bA:0:0:1:21:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O X O |
    | X O | | O O X O |
    | X | | O |
    | X | | O |
    | | X | O |
    | |BAR| |
    | | | |
    | | | X |
    | | | X |
    | O X | | X X |
    | O X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 167 O: 123 X-O: 0-0
    Cube: 1
    X to play 21

    ---
    Tim Chow

    My first inclination was to hit despite seeing that almost 2/3 of Os rolls will hit or make an advanced anchor. Not hitting looked too resigned. But looking at Os rolls after playing the quiet bar/22 reveals a pretty rough position for O. 6s, 3s and 1s
    stink for O. I'd play safe.

    Bob

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Sun Mar 26 09:54:53 2023
    XGID=--aB--DaB---bD---b-e-bB-bA:0:0:1:21:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O X O |
    | X O | | O O X O |
    | X | | O |
    | X | | O |
    | | X | O |
    | |BAR| |
    | | | |
    | | | X |
    | | | X |
    | O X | | X X |
    | O X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 167 O: 123 X-O: 0-0
    Cube: 1
    X to play 21

    Backgammon adages often contradict each other. Magriel's criteria tell
    us to note that X has more checkers back and is anchored while O is not.
    That might seem to suggest a bold play, such as hitting or slotting the
    5pt. But Joe Sylvester famously said, "When defending, make defensive
    plays."

    The trouble with hitting here is that there's not too much upside to be
    had. O has only four dancing rolls, and not very many other bad rolls.
    O has no immediate threat that demands a tempo hit.

    In Variant 1 below, X has a spare on his 8pt to hit with. In Variant 2,
    O has slotted her 5pt, which incentivizes X to hit for tempo.

    1. Rollout¹ Bar/22 eq:-0.319
    Player: 42.94% (G:10.28% B:0.44%)
    Opponent: 57.06% (G:19.11% B:0.47%)
    Confidence: ±0.014 (-0.333..-0.305) - [100.0%]

    2. Rollout¹ Bar/23 6/5 eq:-0.455 (-0.136)
    Player: 42.34% (G:9.82% B:0.46%)
    Opponent: 57.66% (G:28.60% B:0.84%)
    Confidence: ±0.016 (-0.471..-0.439) - [0.0%]

    3. Rollout¹ Bar/23 8/7* eq:-0.464 (-0.145)
    Player: 42.17% (G:10.60% B:0.49%)
    Opponent: 57.83% (G:30.14% B:1.15%)
    Confidence: ±0.013 (-0.477..-0.452) - [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

    ---------
    Variant 1
    ---------

    XGID=--aB--DaC---bC---b-e-bB-bA:0:0:1:21:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O X O |
    | X O | | O O X O |
    | X | | O |
    | | | O |
    | | X | O |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | O X | | X X |
    | O X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 162 O: 123 X-O: 0-0
    Cube: 1
    X to play 21

    1. Rollout¹ Bar/23 8/7* eq:-0.216
    Player: 46.41% (G:13.29% B:0.59%)
    Opponent: 53.59% (G:22.48% B:0.78%)
    Confidence: ±0.017 (-0.233..-0.199) - [100.0%]

    2. Rollout¹ Bar/22 eq:-0.274 (-0.058)
    Player: 43.52% (G:10.99% B:0.40%)
    Opponent: 56.48% (G:16.88% B:0.40%)
    Confidence: ±0.014 (-0.288..-0.261) - [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

    ---------
    Variant 2
    ---------

    XGID=--aB--DaB---cD---b-cabB-bA:0:0:1:21:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X O |
    | X O | | O O X O |
    | X | | O |
    | X | | |
    | | X | |
    | |BAR| |
    | | | |
    | | | X |
    | O | | X |
    | O X | | X X |
    | O X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 167 O: 129 X-O: 0-0
    Cube: 1
    X to play 21

    1. Rollout¹ Bar/23 8/7* eq:-0.452
    Player: 41.22% (G:11.13% B:0.53%)
    Opponent: 58.78% (G:26.88% B:1.05%)
    Confidence: ±0.012 (-0.464..-0.441) - [97.9%]

    2. Rollout¹ Bar/22 eq:-0.469 (-0.016)
    Player: 38.89% (G:9.66% B:0.40%)
    Opponent: 61.11% (G:19.04% B:0.52%)
    Confidence: ±0.011 (-0.479..-0.458) - [2.1%]

    3. Rollout¹ Bar/23 6/5 eq:-0.483 (-0.031)
    Player: 40.85% (G:10.87% B:0.52%)
    Opponent: 59.15% (G:27.41% B:0.85%)
    Confidence: ±0.011 (-0.494..-0.473) - [0.0%]

    ¹ 2592 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller

    eXtreme Gammon Version: 2.19.211.pre-release

    ---
    Tim Chow

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