• A two-part problem

    From pepstein5@gmail.com@21:1/5 to All on Sun Aug 14 04:31:53 2022
    In the position below, it is obvious that I should double.
    So my question 1 is why might I (a reasonably strong player)
    go ahead and roll anyway without doubling when I'm playing XG?

    Question 2 is where you get the chance to outsmart XG.
    (How exciting!)
    Here, I actually did double and XG blundered according to its own rollout.
    Can you make the correct take/pass decision and thereby outplay XG?

    (The answer is not that you should have two versions of XG and ask one of
    them: "If I were to ask the other version of XG whether this is a take, what would the other version say?" and then make the other play.)

    Paul

    XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
    X:Daniel O:eXtremeGammon

    Score is X:0 O:2. Unlimited Game, Jacoby Beaver
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X | | X O O O O O |
    | X | | O O O O O |
    | X | | O O O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 66 X-O: 0-2
    Cube: 4, X own cube
    X on roll, cube action

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Sun Aug 14 09:30:47 2022
    On 8/14/2022 7:31 AM, peps...@gmail.com wrote:
    XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
    X:Daniel O:eXtremeGammon

    Score is X:0 O:2. Unlimited Game, Jacoby Beaver
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X | | X O O O O O |
    | X | | O O O O O |
    | X | | O O O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 66 X-O: 0-2
    Cube: 4, X own cube
    X on roll, cube action

    I find these cube decisions difficult. O still has a five-point board
    and a big lead in the pip count, and there is some chance X won't make
    a five-prime right away. I'll take this one.

    ---
    Tim Chow

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  • From ah...Clem@21:1/5 to peps...@gmail.com on Mon Aug 15 08:50:52 2022
    On 8/14/2022 7:31 AM, peps...@gmail.com wrote:


    XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
    X:Daniel O:eXtremeGammon

    Score is X:0 O:2. Unlimited Game, Jacoby Beaver
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X | | X O O O O O |
    | X | | O O O O O |
    | X | | O O O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 66 X-O: 0-2
    Cube: 4, X own cube
    X on roll, cube action

    1) Looks like a pretty clear take since O has a strong board and a race
    lead. Regardless, cubing gives your opponent a chance to make a mistake
    while holding doesn't so I can't think of a reason to hold. Especially
    since you say XG muffed the take.

    2) See 1) above.

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  • From pepstein5@gmail.com@21:1/5 to ah...Clem on Mon Aug 15 12:25:07 2022
    On Monday, August 15, 2022 at 1:50:56 PM UTC+1, ah...Clem wrote:
    On 8/14/2022 7:31 AM, peps...@gmail.com wrote:


    XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
    X:Daniel O:eXtremeGammon

    Score is X:0 O:2. Unlimited Game, Jacoby Beaver +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X | | X O O O O O |
    | X | | O O O O O |
    | X | | O O O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 131 O: 66 X-O: 0-2
    Cube: 4, X own cube
    X on roll, cube action
    1) Looks like a pretty clear take since O has a strong board and a race lead. Regardless, cubing gives your opponent a chance to make a mistake while holding doesn't so I can't think of a reason to hold. Especially
    since you say XG muffed the take.

    2) See 1) above.

    The reason I might hold is that, as I stated in another thread, I sometimes have trouble
    with the XG app on my computer so I sometimes roll accidentally while trying to double.
    It's incredibly annoying.

    It's actually a clear pass, according to XG's rollout which is what I thought. I was surprised
    by XG's take. I didn't say that XG muffed the take. I said that XG made the wrong decision.
    XG wrongly took when it should have passed. However, XG's bad take was validated when
    it beat me. My memory is that I rolled a 53 which I think is an excellent roll. We can't quite
    call it a joker though because I'm a big fave to make the 5 point board. I played this 19/14 7/4
    which I think is correct. XG rolled its miracle 61 to leap my prime. I then missed the triple shot and
    XG doubled me out.
    XG's board is currently strong but it's a big fave to weaken soon. XG does get more gammons than
    I do, but only slightly more.

    Analyzed in Rollout
    No redouble
    Player Winning Chances: 79.73% (G:4.21% B:0.06%)
    Opponent Winning Chances: 20.27% (G:5.98% B:0.03%)
    Redouble/Take
    Player Winning Chances: 80.99% (G:4.67% B:0.11%)
    Opponent Winning Chances: 19.01% (G:5.98% B:0.04%)

    Cubeless Equities: No Double=+0.577, Double=+1.215

    Cubeful Equities:
    No redouble: +0.874 (-0.126)
    Redouble/Take: +1.147 (+0.147)
    Redouble/Pass: +1.000

    Best Cube action: Redouble / Pass

    Rollout:
    1296 Games rolled with Variance Reduction.
    Moves: 3-ply, cube decisions: XG Roller
    Confidence No Double: ± 0.007 (+0.867..+0.881)
    Confidence Double: ± 0.010 (+1.138..+1.157)

    Double Decision confidence: 100.0%
    Take Decision confidence: 100.0%

    Duration: 18 minutes 04 seconds

    eXtreme Gammon Version: 2.10

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Tue Aug 16 09:05:52 2022
    On 8/15/2022 3:25 PM, peps...@gmail.com wrote:
    It's actually a clear pass, according to XG's rollout which is what I thought.

    Interesting. Even after I made some significant improvements to XG's
    position, it rolled out to a pass:

    XGID=-a--ABBCB-A--C----Accbbbb-:2:1:1:00:0:0:3:0:10

    X:Player 1 O:Player 2
    Score is X:0 O:0. Unlimited Game, Jacoby Beaver
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X X | | O O O O O O |
    | X | | O O O O O O |
    | X | | O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 130 O: 77 X-O: 0-0
    Cube: 4, X own cube
    X on roll, cube action

    Analyzed in Rollout
    No redouble
    Player Winning Chances: 77.67% (G:3.92% B:0.06%)
    Opponent Winning Chances: 22.33% (G:6.34% B:0.08%)
    Redouble/Take
    Player Winning Chances: 79.09% (G:4.59% B:0.12%)
    Opponent Winning Chances: 20.91% (G:6.97% B:0.08%)

    Cubeful Equities:
    No redouble: +0.818 (-0.182)
    Redouble/Take: +1.055 (+0.055)
    Redouble/Pass: +1.000

    Best Cube action: Redouble / Pass

    Rollout:
    1296 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller
    Confidence No Double: ± 0.006 (+0.812..+0.824)
    Confidence Double: ± 0.011 (+1.044..+1.065)

    eXtreme Gammon Version: 2.19.207.pre-release

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  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Tue Aug 16 09:23:49 2022
    On Tuesday, August 16, 2022 at 2:05:59 PM UTC+1, Tim Chow wrote:
    On 8/15/2022 3:25 PM, peps...@gmail.com wrote:
    It's actually a clear pass, according to XG's rollout which is what I thought.
    Interesting. Even after I made some significant improvements to XG's position, it rolled out to a pass:

    XGID=-a--ABBCB-A--C----Accbbbb-:2:1:1:00:0:0:3:0:10

    X:Player 1 O:Player 2
    Score is X:0 O:0. Unlimited Game, Jacoby Beaver +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X X | | O O O O O O |
    | X | | O O O O O O |
    | X | | O O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | | +---+
    | X X | | X X | | 4 |
    | X X X | | X X X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 130 O: 77 X-O: 0-0
    Cube: 4, X own cube
    X on roll, cube action
    Analyzed in Rollout
    No redouble
    Player Winning Chances: 77.67% (G:3.92% B:0.06%)
    Opponent Winning Chances: 22.33% (G:6.34% B:0.08%)
    Redouble/Take
    Player Winning Chances: 79.09% (G:4.59% B:0.12%)
    Opponent Winning Chances: 20.91% (G:6.97% B:0.08%)

    Cubeful Equities:
    No redouble: +0.818 (-0.182)
    Redouble/Take: +1.055 (+0.055)
    Redouble/Pass: +1.000

    Best Cube action: Redouble / Pass

    Rollout:
    1296 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller
    Confidence No Double: ± 0.006 (+0.812..+0.824)
    Confidence Double: ± 0.011 (+1.044..+1.065)

    eXtreme Gammon Version: 2.19.207.pre-release

    Our position is obviously stronger than it appears to you and Walt.
    One consideration is that it's very hard for XG to hit a shot on XG's next roll.
    That fact is reflected in XG's low gammon count. I think that 55 is our only roll which
    concedes a direct shot.
    When superficially similar positions are takes, it's often because the opponent has already
    removed a checker and therefore can't lose a gammon.
    I'm sure you can readily get takes by variantizing that way.
    As far as I can see, XG's good scenario is that 1) I fail to make the 5 prime. 2) XG leaps.
    3) I miss the shot.

    That's quite a parlay -- I'm surprised these aren't even bigger passes than they are.

    Paul

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Tue Aug 16 21:16:33 2022
    On 8/16/2022 12:23 PM, peps...@gmail.com wrote:
    As far as I can see, XG's good scenario is that 1) I fail to make the 5 prime. 2) XG leaps.
    3) I miss the shot.

    Because the pip count lead is so large, XG has multiple
    opportunities to leap your five-prime. If you hit loose
    then XG could hit back and leap your prime when you're
    dancing. If XG leaps and you hit, it could leap a second
    time.

    ---
    Tim Chow

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