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  • Backgamee play

    From Timothy Chow@21:1/5 to All on Fri Oct 7 21:44:03 2022
    XGID=-bbBBAEb--------------g-b-:1:-1:1:31:0:0:0:0:10
    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-+
    | | | O O | +---+
    | | | O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | 7 |
    | |BAR| |
    | | | X |
    | | | X |
    | | | X |
    | O | | X X X O O |
    | O | | X X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 49 O: 153 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    ---
    Tim Chow

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  • From [email protected]@21:1/5 to Tim Chow on Sat Oct 8 03:13:39 2022
    On Saturday, October 8, 2022 at 2:44:08 AM UTC+1, Tim Chow wrote:
    XGID=-bbBBAEb--------------g-b-:1:-1:1:31:0:0:0:0:10
    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-+
    | | | O O | +---+
    | | | O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | 7 |
    | |BAR| |
    | | | X |
    | | | X |
    | | | X |
    | O | | X X X O O |
    | O | | X X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 49 O: 153 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    ---
    Tim Chow

    This is a highly unusual position in that the opponent's inner board is so awful despite their anchors.
    So the non-expert player's intuition is likely to be skewed and a strange QF play is likely to be correct.
    Despite all this, leaving a shot must be bad. Sure, being hit won't usually lose, but it will surely
    needlessly compromise our gammon chances.

    So the candidates are 6/3 6/5 and 6/3 5/4
    5/4 must be the QF play and there is a competitive nature in me which wants to be right.
    But it seems like a copout to just give 5/4 right away without any analysis. Let's count the shotleavers. That might be why 5/4 is right.
    Maybe just a crude count of all the blotting numbers ignoring the number of hits for the opponent.
    6/5 blots to any 6 apart from 63, 54, 53, 43, 22.
    This is 16 numbers.
    5/4 blots to 41 and I think that's it.
    6/3 5/4 must be correct.
    It's quite possible that I counted somewhat Waltishly -- I didn't check as much as usual.
    But, even allowing for possible inaccuracies in the count, 6/3 5/4 must be correct, and it must be
    an easy problem.

    I think that some problems have a message of "Avoid this blunder" rather than "Try to figure out the play."
    More a cautionary tale than a problem. Tim, which one of Hilaire Belloc's Cautionary Tales quotes this
    position? I had no idea that he played backgammon.

    Paul

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  • From Timothy Chow@21:1/5 to All on Mon Oct 10 08:45:04 2022
    XGID=-bbBBAEb--------------g-b-:1:-1:1:31:0:0:0:0:10
    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-+
    | | | O O | +---+
    | | | O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | 7 |
    | |BAR| |
    | | | X |
    | | | X |
    | | | X |
    | O | | X X X O O |
    | O | | X X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 49 O: 153 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    Paul gave a good analysis. In practice, the challenge here is to
    avoid playing on autopilot; it's easy to hastily conclude that
    6/5 6/3 is "forced," or to automatically clear from the rear since
    that is normally the right strategy in this sort of position.

    1. Rollout¹ 6/3 5/4 eq:+1.589
    Player: 92.79% (G:61.65% B:14.56%)
    Opponent: 7.21% (G:0.00% B:0.00%)
    Confidence: ±0.012 (+1.577..+1.601) - [100.0%]

    2. Rollout¹ 6/5 6/3 eq:+1.489 (-0.100)
    Player: 91.47% (G:57.31% B:11.75%)
    Opponent: 8.53% (G:0.00% B:0.00%)
    Confidence: ±0.012 (+1.477..+1.501) - [0.0%]

    ¹ 1296 Games rolled with Variance Reduction.
    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 Stick Rice@21:1/5 to Tim Chow on Mon Oct 10 12:17:18 2022
    On Friday, October 7, 2022 at 9:44:08 PM UTC-4, Tim Chow wrote:
    XGID=-bbBBAEb--------------g-b-:1:-1:1:31:0:0:0:0:10
    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-+
    | | | O O | +---+
    | | | O O | | 2 |
    | | | O | +---+
    | | | O |
    | | | 7 |
    | |BAR| |
    | | | X |
    | | | X |
    | | | X |
    | O | | X X X O O |
    | O | | X X X X O O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 49 O: 153 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    ---
    Tim Chow

    I would no longer refer to the on roll player as a backgamee because there is no longer a backgame in effect. The other player's forward position makes this a busted position, nothing else.

    Stick

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  • From Timothy Chow@21:1/5 to All on Tue Jan 2 22:36:36 2024
    In a backgame, I refer to the player who is playing the backgame as
    the "backgamer" and the other player as the "backgamee." This
    terminology seems logical to me, though I don't know if anyone else
    uses it. Similarly, I use the terms "holder" and "holdee" when it's
    a holding game.

    XGID=-bCbBCCAAAA------bacb-ba--:1:-1:1:31:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | O O | | O O O O | +---+
    | O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | X X X |
    | | | X X X O X O |
    | X X X X | | X X X O X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 81 O: 151 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to Stick Rice on Thu Jan 4 09:17:36 2024
    On 1/3/2024 5:48 PM, Stick Rice wrote:
    When the terms are so similar I don't think we get much mileage out of using them. Instead I prefer saying it the long way such as "I was playing a backgame" or "I was playing against a backgame".

    I use them when categorizing decisions as "backgamer cubes" versus
    "backgamee cubes" or "backgamer checker plays" versus "backgamee
    checker plays." It's also convenient if one wants to say something
    like, "A common backgamee tactic is to banana split, to force the
    backgamer to hit and recirculate the backgamee's checkers."

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Thu Jan 4 09:26:02 2024
    XGID=-bCbBCCAAAA------bacb-ba--:1:-1:1:31:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | O O | | O O O O | +---+
    | O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | | | X X X |
    | | | X X X O X O |
    | X X X X | | X X X O X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 81 O: 151 X-O: 0-0
    Cube: 2, O own cube
    X to play 31

    Prime or clear? The conventional wisdom is that the backgamee should
    strive to prime the backgamer, but this advice does not necessarily
    apply late in the game, especially if the backgamee is losing the
    timing battle. X can prime with 10/7 9/8, but he can't expect to hold
    the prime long enough to force O to crunch, so X is well advised not
    to create points that he may have difficulty clearing safely.

    1. Rollout¹ 9/8 7/4 eq:+0.510
    Player: 66.61% (G:29.60% B:3.55%)
    Opponent: 33.39% (G:1.61% B:0.05%)
    Confidence: ±0.009 (+0.502..+0.519) - [100.0%]

    2. Rollout¹ 9/6 8/7 eq:+0.426 (-0.084)
    Player: 65.06% (G:25.37% B:2.44%)
    Opponent: 34.94% (G:1.49% B:0.04%)
    Confidence: ±0.009 (+0.417..+0.435) - [0.0%]

    3. Rollout¹ 10/7 8/7 eq:+0.422 (-0.088)
    Player: 65.37% (G:24.57% B:2.55%)
    Opponent: 34.63% (G:2.20% B:0.07%)
    Confidence: ±0.009 (+0.414..+0.431) - [0.0%]

    4. Rollout¹ 10/7 9/8 eq:+0.373 (-0.137)
    Player: 63.62% (G:24.62% B:2.15%)
    Opponent: 36.38% (G:2.53% B:0.09%)
    Confidence: ±0.009 (+0.364..+0.382) - [0.0%]

    5. Rollout¹ 10/9 7/4 eq:+0.359 (-0.151)
    Player: 62.18% (G:27.02% B:3.36%)
    Opponent: 37.82% (G:2.90% B:0.10%)
    Confidence: ±0.009 (+0.350..+0.368) - [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 Timothy Chow@21:1/5 to Stick Rice on Fri Jan 5 08:30:59 2024
    On 1/5/2024 4:52 AM, Stick Rice wrote:
    Maybe it's just me because I'm not that bright but probably for others too but when I read backgamee or backgamer for eg I have to stop and think about what you mean. I wouldn't think it helps readers out. For personal use it's understandable if that'
    s what you want. For the public I don't see it ever catching on and it comes off as more of a hindrance than an aide. Just my half cent.

    All terminology seems unfamiliar at first. Think about Nactation.

    Whether it catches on has less to do with the terminology itself
    and more to do with who is using the terminology. Of course if a
    nobody like myself uses it, it won't catch on. If a 'celebrity'
    in the backgammon world starts using it, then it will definitely
    catch on no matter how bad the terminology is. As I recall, you
    hate Michy's use of "double tiger." But because Michy is using it,
    it's catching on.

    ---
    Tim Chow

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