• Just make the 5 pt... but what a blunder!

    From BlueDice@21:1/5 to All on Thu Nov 11 08:53:11 2021
    Complete with XGR++ analysis.
    Witness statements in defence of XG please.
    Adapted from a facebook>>Backgammon strategy post.

    XGID=--aB--DbB--CaD---bac-bab--:0:0:1:61:0:0:0:0:10
    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 O O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X X O | | X X |
    | O X X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 128 X-O: 0-0
    Cube: 1
    X to play 61

    1. XG Roller++ 13/12* 12/6 eq:+0.491
    Player: 62.76% (G:13.46% B:0.49%)
    Opponent: 37.24% (G:7.27% B:0.15%)

    2. XG Roller++ 13/12* 11/5 eq:+0.248 (-0.243)
    Player: 57.10% (G:15.48% B:0.79%)
    Opponent: 42.90% (G:15.43% B:0.36%)

    3. XG Roller++ 11/5 6/5 eq:+0.230 (-0.261)
    Player: 56.56% (G:5.12% B:0.20%)
    Opponent: 43.44% (G:3.41% B:0.04%)

    eXtreme Gammon Version: 2.19.211.pre-release
    --
    BD

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Stick Rice@21:1/5 to Tim Chow on Thu Nov 11 20:55:38 2021
    On Thursday, November 11, 2021 at 11:31:43 PM UTC-5, Tim Chow wrote:
    On 11/11/2021 11:53 AM, BlueDice wrote:
    XGID=--aB--DbB--CaD---bac-bab--:0:0:1:61:0:0:0:0:10
    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 O O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X X O | | X X |
    | O X X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 128 X-O: 0-0
    Cube: 1
    X to play 61
    Nice one! Here's how I'm inclined to view this position, after
    playing around with it a bit. Does X want to attack, race, or
    prime? I'd say that if X wants to try to prime, then he should
    make the 5pt, but if he wants to try attacking or racing, then
    he should play 13/12*/6. The trouble with making the 5pt is that
    it's hard to prime O in this position. Either attacking or trying
    to gain pips in the race is more promising.

    Below are two variants which might help shed some light.

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

    XGID=--aB--DcB--CaD---b-c-bab--:0:0:1:61:0:0:0:0:10
    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 O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X O | | X |
    | X X O | | X X |
    | O X X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 139 X-O: 0-0
    Cube: 1
    X to play 61
    1. Rollout¹ 13/12* 12/6 eq:+0.721
    Player: 67.24% (G:16.78% B:0.54%)
    Opponent: 32.76% (G:6.73% B:0.16%)
    Confidence: ±0.011 (+0.710..+0.732) - [100.0%]

    2. Rollout¹ 11/5 6/5 eq:+0.564 (-0.157)
    Player: 65.95% (G:7.67% B:0.24%)
    Opponent: 34.05% (G:3.48% B:0.07%)
    Confidence: ±0.011 (+0.553..+0.575) - [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 2
    ---------

    XGID=--aBa-DbB--CaD---b-c-bab--:0:0:1:61:0:0:0:0:10
    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 O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X X O | | X X |
    | O X X O | | X O X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 142 X-O: 0-0
    Cube: 1
    X to play 61
    1. Rollout¹ 11/5 6/5 eq:+0.702
    Player: 68.00% (G:11.93% B:0.45%)
    Opponent: 32.00% (G:4.15% B:0.10%)
    Confidence: ±0.009 (+0.693..+0.711) - [97.3%]

    2. Rollout¹ 13/12* 12/6 eq:+0.689 (-0.013)
    Player: 66.64% (G:16.65% B:0.73%)
    Opponent: 33.36% (G:7.25% B:0.18%)
    Confidence: ±0.009 (+0.680..+0.698) - [2.7%]

    ¹ 2592 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

    Looking at the dice distribution after each play makes it clear.

    Stick

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to BlueDice on Thu Nov 11 23:31:38 2021
    On 11/11/2021 11:53 AM, BlueDice wrote:
    XGID=--aB--DbB--CaD---bac-bab--:0:0:1:61:0:0:0:0:10
    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 O O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X X O | | X X |
    | O X X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 128 X-O: 0-0
    Cube: 1
    X to play 61

    Nice one! Here's how I'm inclined to view this position, after
    playing around with it a bit. Does X want to attack, race, or
    prime? I'd say that if X wants to try to prime, then he should
    make the 5pt, but if he wants to try attacking or racing, then
    he should play 13/12*/6. The trouble with making the 5pt is that
    it's hard to prime O in this position. Either attacking or trying
    to gain pips in the race is more promising.

    Below are two variants which might help shed some light.

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

    XGID=--aB--DcB--CaD---b-c-bab--:0:0:1:61:0:0:0:0:10

    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 O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X O | | X |
    | X X O | | X X |
    | O X X O | | X X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 139 X-O: 0-0
    Cube: 1
    X to play 61

    1. Rollout¹ 13/12* 12/6 eq:+0.721
    Player: 67.24% (G:16.78% B:0.54%)
    Opponent: 32.76% (G:6.73% B:0.16%)
    Confidence: ±0.011 (+0.710..+0.732) - [100.0%]

    2. Rollout¹ 11/5 6/5 eq:+0.564 (-0.157)
    Player: 65.95% (G:7.67% B:0.24%)
    Opponent: 34.05% (G:3.48% B:0.07%)
    Confidence: ±0.011 (+0.553..+0.575) - [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 2
    ---------

    XGID=--aBa-DbB--CaD---b-c-bab--:0:0:1:61:0:0:0:0:10

    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 O O |
    | X O | | O O O |
    | X | | O |
    | X | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X | | X |
    | X X O | | X X |
    | O X X O | | X O X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 142 X-O: 0-0
    Cube: 1
    X to play 61

    1. Rollout¹ 11/5 6/5 eq:+0.702
    Player: 68.00% (G:11.93% B:0.45%)
    Opponent: 32.00% (G:4.15% B:0.10%)
    Confidence: ±0.009 (+0.693..+0.711) - [97.3%]

    2. Rollout¹ 13/12* 12/6 eq:+0.689 (-0.013)
    Player: 66.64% (G:16.65% B:0.73%)
    Opponent: 33.36% (G:7.25% B:0.18%)
    Confidence: ±0.009 (+0.680..+0.698) - [2.7%]

    ¹ 2592 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)