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  • 4pt vs 7pt 3

    From Timothy Chow@21:1/5 to All on Wed Jun 14 08:30:30 2023
    XGID=-b-B-BD-C----Aa-cbbcbC----:1:-1:1:11:0:0:0:0:10

    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 | | O O X | +---+
    | O O O | | O O X | | 2 |
    | O | | O X | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X | | X X X O |
    | X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 140 O: 144 X-O: 0-0
    Cube: 2, O own cube
    X to play 11

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From ah....Clem@21:1/5 to Timothy Chow on Wed Jun 14 08:50:07 2023
    On 6/14/2023 8:30 AM, Timothy Chow wrote:
    XGID=-b-B-BD-C----Aa-cbbcbC----:1:-1:1:11:0:0:0:0:10

    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 |   | O  O  X          | +---+
     |          O  O  O |   | O  O  X          | | 2 |
     |          O       |   | O     X          | +---+
     |                  |   |                  |
     |                  |   |                  |
     |                  |BAR|                  |
     |                  |   |                  |
     |                  |   | X                |
     |             X    |   | X                |
     |             X    |   | X  X     X     O |
     |             X    |   | X  X     X     O |
     +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count  X: 140  O: 144 X-O: 0-0
    Cube: 2, O own cube
    X to play 11



    Tim's observation that making the four point is usually better when
    there are blots to be picked up seems to apply here, or rather it might
    in reverse.

    Initially, it seems like blocking sixes would be stronger than filling
    in the four point. OTOH, making the four gives a solid four prime and
    makes a fifth point. An observation of my own is that it's usually
    better to make an additional point than shifting one already made.

    So, I'll make the four point here.

    --
    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 Fri Jun 16 08:15:04 2023
    XGID=-b-B-BD-C----Aa-cbbcbC----:1:-1:1:11:0:0:0:0:10

    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 | | O O X | +---+
    | O O O | | O O X | | 2 |
    | O | | O X | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X | | X X X O |
    | X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 140 O: 144 X-O: 0-0
    Cube: 2, O own cube
    X to play 11

    I said that playing 6/4(2) with snake eyes is usually better than making
    the bar point, if the 5pt is made and O has blots. XG says that this
    position is an exception. What gives?

    Well, first of all, the rollout below says that 6/4(2) is only a 0.05
    error, which is not huge IMO. But the main point is that this position
    is absolutely a priming battle, and 8/7(3) 6/5 is a superior priming
    play. We really don't want O to be able to escape a back checker with
    a 6, and 8/7(3) 6/5 also gives us good chances of making the 4pt.

    See also the variant, which is still a priming battle, but slightly
    less so since O has only a four-prime and not a five-prime. There,
    6/4(2) edges out making the bar point according to the rollout.

    1. Rollout¹ 8/7(3) 6/5 eq:-0.036
    Player: 54.08% (G:15.93% B:0.53%)
    Opponent: 45.92% (G:8.91% B:0.31%)
    Confidence: ±0.009 (-0.045..-0.026) - [100.0%]

    2. Rollout¹ 6/4(2) eq:-0.086 (-0.050)
    Player: 51.64% (G:16.71% B:0.50%)
    Opponent: 48.36% (G:8.60% B:0.29%)
    Confidence: ±0.010 (-0.096..-0.076) - [0.0%]

    3. Rollout¹ 13/12 8/7(2) 6/5 eq:-0.090 (-0.054)
    Player: 52.59% (G:15.43% B:0.56%)
    Opponent: 47.41% (G:9.90% B:0.30%)
    Confidence: ±0.011 (-0.101..-0.079) - [0.0%]

    4. Rollout¹ 13/12 8/7(3) eq:-0.098 (-0.062)
    Player: 52.08% (G:14.87% B:0.49%)
    Opponent: 47.92% (G:9.20% B:0.31%)
    Confidence: ±0.010 (-0.108..-0.089) - [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
    -------

    XGID=-b-B-BD-C----Aab-bccbC----:1:-1:1:11:0:0:0:0:10

    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 | | O O X | +---+
    | O O O | | O O X | | 2 |
    | O | | O X | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X | | X X X O |
    | X | | X X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 140 O: 144 X-O: 0-0
    Cube: 2, O own cube
    X to play 11

    1. Rollout¹ 6/4(2) eq:+0.045
    Player: 55.91% (G:18.77% B:0.62%)
    Opponent: 44.09% (G:8.32% B:0.31%)
    Confidence: ±0.010 (+0.035..+0.055) - [100.0%]

    2. Rollout¹ 13/12 8/7(2) 6/5 eq:+0.012 (-0.033)
    Player: 55.62% (G:17.72% B:0.70%)
    Opponent: 44.38% (G:9.71% B:0.39%)
    Confidence: ±0.010 (+0.002..+0.023) - [0.0%]

    3. Rollout¹ 8/7(3) 6/5 eq:+0.003 (-0.042)
    Player: 54.92% (G:17.31% B:0.69%)
    Opponent: 45.08% (G:8.87% B:0.34%)
    Confidence: ±0.011 (-0.008..+0.014) - [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)