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  • 4pt vs 7pt 14

    From Timothy Chow@21:1/5 to All on Sat Jul 15 09:02:18 2023
    Final problem in this series. It might look a bit like
    problem #11, but pay attention to the differences!

    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
    | X O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Renan Moritz@21:1/5 to Timothy Chow on Sat Jul 15 14:43:59 2023
    On Saturday, July 15, 2023 at 10:02:21 AM UTC-3, Timothy Chow wrote:
    Final problem in this series. It might look a bit like
    problem #11, but pay attention to the differences!

    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
    | X O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    ---
    Tim Chow

    Make the four!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From ah....Clem@21:1/5 to Timothy Chow on Sun Jul 16 16:35:34 2023
    On 7/15/2023 9:02 AM, Timothy Chow wrote:
    Final problem in this series.  It might look a bit like
    problem #11, but pay attention to the differences!

    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
     | X           O    |   | O                |
     |                  |   | O                |
     |                  |   |                  |
     |                  |BAR|                  |
     |                  |   | X                |
     | O                |   | X                |
     | O           X    |   | X                |
     | O           X    |   | X                |
     | O     X  X  X    |   | X        O     O |
     +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count  X: 160  O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    Whack two checkers? Always worth a good look...

    Making the four point exposes a direct shot at the blot on the nine,
    while making the bar point only exposes an indirect shot. Race will be
    almost even after this play and O has a slightly better board, so safe
    play is indicated.

    Two checkers back implies prime rather than attack, so I'll make the
    four point. But won't be surprised if XG whacks two.

    --
    Ah....Clem
    The future is fun, the future is fair.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Mon Jul 17 08:45:36 2023
    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
    | X O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    In Problem 11, we noted that making the 4pt seemed to be the natural
    play at first glance, unstacking the 6pt and preparing for a fight.
    However, X had escaped both back checkers and had a big stack on his
    midpoint, and making the bar point was XG's choice there. But here,
    there's less reason to make the bar point. Making the 4pt does leave
    a direct shot, but because X has two checkers back and will have equal
    board strength after the play, Magriel's criteria suggest that he can
    play somewhat boldly. Making the bar point also strips the midpoint
    instead of unstacking a heavy point.

    1. Rollout¹ 10/4 6/4 eq:-0.075
    Player: 48.33% (G:15.22% B:0.66%)
    Opponent: 51.67% (G:16.43% B:1.11%)
    Confidence: ±0.015 (-0.090..-0.060) - [100.0%]

    2. Rollout¹ 13/7 9/7 eq:-0.156 (-0.081)
    Player: 46.60% (G:13.71% B:0.66%)
    Opponent: 53.40% (G:16.81% B:1.12%)
    Confidence: ±0.015 (-0.170..-0.141) - [0.0%]

    3. Rollout¹ 9/3* 3/1* eq:-0.238 (-0.163)
    Player: 44.38% (G:14.32% B:0.42%)
    Opponent: 55.62% (G:18.23% B:1.28%)
    Confidence: ±0.014 (-0.252..-0.223) - [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)
  • From ah....Clem@21:1/5 to ah....Clem on Mon Jul 17 11:14:02 2023
    On 7/16/2023 4:35 PM, ah....Clem wrote:
    On 7/15/2023 9:02 AM, Timothy Chow wrote:
    Final problem in this series.  It might look a bit like
    problem #11, but pay attention to the differences!

    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
      | X           O    |   | O                |
      |                  |   | O                |
      |                  |   |                  |
      |                  |BAR|                  |
      |                  |   | X                |
      | O                |   | X                |
      | O           X    |   | X                |
      | O           X    |   | X                |
      | O     X  X  X    |   | X        O     O |
      +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count  X: 160  O: 152 X-O: 0-0
    Cube: 1
    X to play 62

    Whack two checkers?  Always worth a good look...

    Making the four point exposes a direct shot at the blot on the nine,
    while making the bar point only exposes an indirect shot.  Race will be almost even after this play and O has a slightly better board, so safe
    play is indicated.

    Two checkers back implies prime rather than attack, so I'll make the
    four point. But won't be surprised if XG whacks two.


    I meant make the bar point. Haven't looked at the rollout yet. Priming position, safe play...

    --
    Ah....Clem
    The future is fun, the future is fair.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Renan Moritz@21:1/5 to Timothy Chow on Mon Jul 17 08:15:32 2023
    On Monday, July 17, 2023 at 9:45:39 AM UTC-3, Timothy Chow wrote:
    XGID=-a-a--E-CAA-dC---c-d--b-B-: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 |
    | X O | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X | | X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 152 X-O: 0-0
    Cube: 1
    X to play 62
    In Problem 11, we noted that making the 4pt seemed to be the natural
    play at first glance, unstacking the 6pt and preparing for a fight.
    However, X had escaped both back checkers and had a big stack on his midpoint, and making the bar point was XG's choice there. But here,
    there's less reason to make the bar point. Making the 4pt does leave
    a direct shot, but because X has two checkers back and will have equal
    board strength after the play, Magriel's criteria suggest that he can
    play somewhat boldly. Making the bar point also strips the midpoint
    instead of unstacking a heavy point.

    1. Rollout¹ 10/4 6/4 eq:-0.075
    Player: 48.33% (G:15.22% B:0.66%)
    Opponent: 51.67% (G:16.43% B:1.11%)
    Confidence: ±0.015 (-0.090..-0.060) - [100.0%]

    2. Rollout¹ 13/7 9/7 eq:-0.156 (-0.081)
    Player: 46.60% (G:13.71% B:0.66%)
    Opponent: 53.40% (G:16.81% B:1.12%)
    Confidence: ±0.015 (-0.170..-0.141) - [0.0%]

    3. Rollout¹ 9/3* 3/1* eq:-0.238 (-0.163)
    Player: 44.38% (G:14.32% B:0.42%)
    Opponent: 55.62% (G:18.23% B:1.28%)
    Confidence: ±0.014 (-0.252..-0.223) - [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

    Big difference 1st x 2nd move - very interesting

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