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  • Hit or run?

    From Timothy Chow@21:1/5 to All on Sat Aug 28 08:54:29 2021
    XGID=--a-BBD-BA--dB----bdB-b-b-:1:-1:1:65:0:0:0:0:10

    X:Player 1 O:Player 2
    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O X O O | +---+
    | X O | | O X O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | O | | X |
    | O | | X |
    | O X | | X X X |
    | O X X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 133 O: 121 X-O: 0-0
    Cube: 2, O own cube
    X to play 65

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Mon Aug 30 08:38:59 2021
    XGID=--a-BBD-BA--dB----bdB-b-b-:1:-1:1:65:0:0:0:0:10

    X:Player 1 O:Player 2
    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O X O O | +---+
    | X O | | O X O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | O | | X |
    | O | | X |
    | O X | | X X X |
    | O X X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 133 O: 121 X-O: 0-0
    Cube: 2, O own cube
    X to play 65

    This one surprised me since it broke a number of rules of thumb. XG
    favors the "racing" play 20/9 even though X is not ahead in the race
    and 20/9 gives up the golden anchor, exposing the straggler to attack.
    I suppose XG's play also violates the rule of thumb, "attack a single
    checker and prime two checkers," although that is not a particularly
    reliable rule of thumb anyway.

    Part of the story is that X's board is stronger than O's, so X is not
    in too much danger of being attacked if he runs. In the variant below,
    I have strengthened O's board, and then XG slightly favors attacking
    over running, even though in the variant, O's racing lead has been
    trimmed.

    1. Rollout¹ 20/9 eq:+0.208
    Player: 63.81% (G:15.29% B:0.41%)
    Opponent: 36.19% (G:8.46% B:0.15%)
    Confidence: ±0.007 (+0.201..+0.215) - [100.0%]

    2. Rollout¹ 9/4 8/2* eq:+0.143 (-0.065)
    Player: 58.50% (G:22.29% B:0.35%)
    Opponent: 41.50% (G:8.81% B:0.25%)
    Confidence: ±0.008 (+0.135..+0.151) - [0.0%]

    3. Rollout¹ 9/3 8/3 eq:+0.139 (-0.068)
    Player: 57.74% (G:21.72% B:0.35%)
    Opponent: 42.26% (G:5.99% B:0.12%)
    Confidence: ±0.008 (+0.131..+0.148) - [0.0%]

    4. Rollout¹ 13/2* eq:+0.096 (-0.112)
    Player: 57.81% (G:21.53% B:0.39%)
    Opponent: 42.19% (G:10.68% B:0.30%)
    Confidence: ±0.010 (+0.086..+0.106) - [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

    -------
    Variant
    -------

    XGID=--a-BBD-BA--dB----bdBbb---:1:-1:1:65:0:0:0:0:10

    X:Player 1 O:Player 2
    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O X O O | +---+
    | X O | | O X O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | O | | X |
    | O | | X |
    | O X | | X X X |
    | O X X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 133 O: 127 X-O: 0-0
    Cube: 2, O own cube
    X to play 65

    1. Rollout¹ 9/3 8/3 eq:+0.048
    Player: 55.08% (G:19.41% B:0.29%)
    Opponent: 44.92% (G:5.43% B:0.18%)
    Confidence: ±0.008 (+0.040..+0.056) - [96.1%]

    2. Rollout¹ 9/4 8/2* eq:+0.038 (-0.010)
    Player: 55.05% (G:20.75% B:0.29%)
    Opponent: 44.95% (G:8.70% B:0.34%)
    Confidence: ±0.008 (+0.031..+0.046) - [3.9%]

    3. Rollout¹ 20/9 eq:+0.028 (-0.020)
    Player: 57.59% (G:16.05% B:0.83%)
    Opponent: 42.41% (G:12.74% B:0.39%)
    Confidence: ±0.009 (+0.019..+0.038) - [0.1%]

    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Thu Jun 16 09:04:20 2022
    Yes, "hit or run" and not "hit and run." Hit and run is a crime on
    the highway, and in this position it would be a crime against
    backgammon.

    XGID=--aBBBB-B---bC--cc-dA-b-A-:0:0:1:51:0:0:0:0:10

    X:Player 1 O:Player 2
    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 |
    | X O O | | O O |
    | X O O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | |
    | O X | | X X X X |
    | O X | | X X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 135 O: 130 X-O: 0-0
    Cube: 1
    X to play 51

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Sat Jun 18 11:05:52 2022
    On Thursday, June 16, 2022 at 2:04:24 PM UTC+1, Tim Chow wrote:
    Yes, "hit or run" and not "hit and run." Hit and run is a crime on
    the highway, and in this position it would be a crime against
    backgammon.
    ....

    Sounds like a preamble in the style of Paul Epstein

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From pepstein5@gmail.com@21:1/5 to peps...@gmail.com on Sat Jun 18 11:40:11 2022
    On Saturday, June 18, 2022 at 7:05:54 PM UTC+1, peps...@gmail.com wrote:
    On Thursday, June 16, 2022 at 2:04:24 PM UTC+1, Tim Chow wrote:
    Yes, "hit or run" and not "hit and run." Hit and run is a crime on
    the highway, and in this position it would be a crime against
    backgammon.
    ....

    Sounds like a preamble in the style of Paul Epstein

    Yes, but how about answering the question?
    I like 8/2* which gives a great position in the 2/3 event that the opponent fails back.
    I don't think any of the alternatives offer that much, so that's my play.

    BTW, Tim sometimes posts in the style of Trickster Tim.
    So it can pay to look for obscure plays that don't do either -- don't hit or run.
    I kind of doubt that my play is correct --- too prosaic. But it's definitely my play.

    Paul

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Sun Jun 19 09:46:03 2022
    XGID=--aBBBB-B---bC--cc-dA-b-A-:0:0:1:51:0:0:0:0:10

    X:Player 1 O:Player 2
    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 |
    | X O O | | O O |
    | X O O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | |
    | O X | | X X X X |
    | O X | | X X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 135 O: 130 X-O: 0-0
    Cube: 1
    X to play 51

    I was surprised by how much difference XG thought there was between
    this position and the variant below, in which O has her 4pt instead
    of her 3pt. In the variant, I guess, almost all of O's rolls play
    well, and a tempo hit is more urgent.

    1. Rollout¹ 20/14 eq:+0.539
    Player: 62.51% (G:20.23% B:0.60%)
    Opponent: 37.49% (G:9.78% B:0.46%)
    Confidence: ±0.012 (+0.527..+0.551) - [100.0%]

    2. Rollout¹ 8/2* eq:+0.454 (-0.085)
    Player: 60.24% (G:25.35% B:0.50%)
    Opponent: 39.76% (G:11.97% B:0.96%)
    Confidence: ±0.013 (+0.441..+0.468) - [0.0%]

    3. Rollout¹ 24/23 20/15 eq:+0.448 (-0.091)
    Player: 60.88% (G:19.87% B:0.75%)
    Opponent: 39.12% (G:11.36% B:0.45%)
    Confidence: ±0.014 (+0.434..+0.461) - [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

    -------
    Variant
    -------

    XGID=--aBBBB-B---bC--cc-dAb--A-:0:0:1:51:0:0:0:0:10

    X:Player 1 O:Player 2
    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 |
    | X O O | | O O |
    | X O O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | |
    | O X | | X X X X |
    | O X | | X X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 135 O: 132 X-O: 0-0
    Cube: 1
    X to play 51

    1. Rollout¹ 8/2* eq:+0.405
    Player: 58.08% (G:24.45% B:0.42%)
    Opponent: 41.92% (G:12.88% B:1.07%)
    Confidence: ±0.010 (+0.394..+0.415) - [100.0%]

    2. Rollout¹ 20/14 eq:+0.357 (-0.048)
    Player: 58.28% (G:18.99% B:0.57%)
    Opponent: 41.72% (G:10.90% B:0.47%)
    Confidence: ±0.014 (+0.342..+0.371) - [0.0%]

    3. Rollout¹ 24/23 20/15 eq:+0.337 (-0.067)
    Player: 58.21% (G:19.04% B:0.61%)
    Opponent: 41.79% (G:11.76% B:0.52%)
    Confidence: ±0.015 (+0.323..+0.352) - [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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Stick Rice@21:1/5 to Tim Chow on Mon Jun 20 00:58:04 2022
    On Sunday, June 19, 2022 at 9:46:08 AM UTC-4, Tim Chow wrote:
    XGID=--aBBBB-B---bC--cc-dA-b-A-:0:0:1:51:0:0:0:0:10

    X:Player 1 O:Player 2
    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 |
    | X O O | | O O |
    | X O O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | |
    | O X | | X X X X |
    | O X | | X X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 135 O: 130 X-O: 0-0
    Cube: 1
    X to play 51
    I was surprised by how much difference XG thought there was between
    this position and the variant below, in which O has her 4pt instead
    of her 3pt. In the variant, I guess, almost all of O's rolls play
    well, and a tempo hit is more urgent.

    1. Rollout¹ 20/14 eq:+0.539
    Player: 62.51% (G:20.23% B:0.60%)
    Opponent: 37.49% (G:9.78% B:0.46%)
    Confidence: ±0.012 (+0.527..+0.551) - [100.0%]

    2. Rollout¹ 8/2* eq:+0.454 (-0.085)
    Player: 60.24% (G:25.35% B:0.50%)
    Opponent: 39.76% (G:11.97% B:0.96%)
    Confidence: ±0.013 (+0.441..+0.468) - [0.0%]

    3. Rollout¹ 24/23 20/15 eq:+0.448 (-0.091)
    Player: 60.88% (G:19.87% B:0.75%)
    Opponent: 39.12% (G:11.36% B:0.45%)
    Confidence: ±0.014 (+0.434..+0.461) - [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

    -------
    Variant
    -------

    XGID=--aBBBB-B---bC--cc-dAb--A-:0:0:1:51:0:0:0:0:10
    X:Player 1 O:Player 2
    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 |
    | X O O | | O O |
    | X O O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | |
    | O X | | X X X X |
    | O X | | X X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 135 O: 132 X-O: 0-0
    Cube: 1
    X to play 51
    1. Rollout¹ 8/2* eq:+0.405
    Player: 58.08% (G:24.45% B:0.42%)
    Opponent: 41.92% (G:12.88% B:1.07%)
    Confidence: ±0.010 (+0.394..+0.415) - [100.0%]

    2. Rollout¹ 20/14 eq:+0.357 (-0.048)
    Player: 58.28% (G:18.99% B:0.57%)
    Opponent: 41.72% (G:10.90% B:0.47%)
    Confidence: ±0.014 (+0.342..+0.371) - [0.0%]

    3. Rollout¹ 24/23 20/15 eq:+0.337 (-0.067)
    Player: 58.21% (G:19.04% B:0.61%)
    Opponent: 41.79% (G:11.76% B:0.52%)
    Confidence: ±0.015 (+0.323..+0.352) - [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

    It's really about how poorly the opp's sixes play when his 3pt is made opposed to his 4pt. Also, I'd have cubed before the roll in the original position but not in the latter. Don't have the time to get into whether cube efficiency matters in the
    positions/plays or not.

    Stick

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Fri May 26 08:31:57 2023
    XGID=-a---aE-C---dFa--b-d-b--A-:0:0:1:62:0:0:0:0:10

    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 |
    | X O | | O O |
    | X | | O |
    | X | | O |
    | 6 | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 155 X-O: 0-0
    Cube: 1
    X to play 62

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Sun May 28 11:34:44 2023
    XGID=-a---aE-C---dFa--b-d-b--A-:0:0:1:62:0:0:0:0:10

    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 |
    | X O | | O O |
    | X | | O |
    | X | | O |
    | 6 | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 155 X-O: 0-0
    Cube: 1
    X to play 62

    Variant 1 below is the variant I had prepared. Then I checked my
    files and I discovered that four years ago, I encountered a position
    (Variant 2) over the board that was very similar to Variant 1. Back
    then I played 13/5*, and this time around I played 24/16.

    1. Rollout¹ 13/5* eq:-0.267
    Player: 44.21% (G:10.87% B:0.50%)
    Opponent: 55.79% (G:18.25% B:0.76%)
    Confidence: ±0.024 (-0.292..-0.243) - [100.0%]

    2. Rollout¹ 24/16 eq:-0.346 (-0.078)
    Player: 43.00% (G:7.96% B:0.36%)
    Opponent: 57.00% (G:20.08% B:0.52%)
    Confidence: ±0.013 (-0.359..-0.332) - [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=-a---aE-C---dF---c-d-b--A-:0:0:1:62:0:0:0:0:10

    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 |
    | X O | | O O |
    | X O | | O |
    | X | | O |
    | 6 | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    1. Rollout¹ 24/16 eq:-0.270
    Player: 44.85% (G:6.95% B:0.32%)
    Opponent: 55.15% (G:17.36% B:0.44%)
    Confidence: ±0.009 (-0.279..-0.262) - [99.8%]

    2. Rollout¹ 13/5* eq:-0.291 (-0.021)
    Player: 43.74% (G:10.52% B:0.48%)
    Opponent: 56.26% (G:18.18% B:0.72%)
    Confidence: ±0.011 (-0.302..-0.280) - [0.2%]

    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

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

    XGID=-a---aE-C---dF---c-db---A-:0:0:1:62:0:0:0:0:10

    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 |
    | X O | | O O |
    | X O | | O |
    | X | | O |
    | 6 | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 154 X-O: 0-0
    Cube: 1
    X to play 62

    1. Rollout¹ 24/16 eq:-0.289
    Player: 44.68% (G:7.53% B:0.33%)
    Opponent: 55.32% (G:18.30% B:0.49%)
    Confidence: ±0.014 (-0.302..-0.275) - [100.0%]

    2. Rollout¹ 13/5* eq:-0.371 (-0.082)
    Player: 41.95% (G:9.97% B:0.44%)
    Opponent: 58.05% (G:18.00% B:0.81%)
    Confidence: ±0.014 (-0.386..-0.357) - [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

    ---
    Tim Chow

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