• Innocuous-looking holdee checker play

    From Timothy Chow@21:1/5 to All on Sat Jan 8 21:24:37 2022
    I've seen some authors refer to positions like the one below as
    "simple." But no quiz position is ever simple. Deceptively simple,
    perhaps, but not simple.

    XGID=-BCBbCB-C-a-----abbcbb----:1:-1:1:62:0:0:0:0:10

    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 O O | +---+
    | O O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | X X |
    | X | | X X O X X X |
    | O X | | X X O X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 65 O: 132 X-O: 0-0
    Cube: 2, O own cube
    X to play 62

    ---
    Tim Chow

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  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Sun Jan 9 14:50:44 2022
    On Sunday, January 9, 2022 at 2:24:39 AM UTC, Tim Chow wrote:
    I've seen some authors refer to positions like the one below as
    "simple." But no quiz position is ever simple. Deceptively simple,
    perhaps, but not simple.

    XGID=-BCBbCB-C-a-----abbcbb----:1:-1:1:62:0:0:0:0:10

    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 O O | +---+
    | O O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | X X |
    | X | | X X O X X X |
    | O X | | X X O X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 65 O: 132 X-O: 0-0
    Cube: 2, O own cube
    X to play 62


    I won't leave a shot (obviously) and I'll make the play that minimises the shotleaving on my next shake.
    I'm hoping that the winning play by my algo is the ugly anti-positional 3/1, because 3/1 would be a nice QF answer
    which would explain why the postion is worth posting.
    The only alternative is 5/3 but then why would Tim post about that, particularly when there's a shortage
    of rigorous beginners' accounts on using forcing to prove independence results in set theory? I'm sure Tim's notes
    could be improved. (I'm reading Weaver at the moment (Nik not Tom).)

    5/3 pays off to 64/61/
    Oh dear. I think they both pay off to the same rolls.
    However 5/3 destroys the stack on the 5 point (duh!) and creates future danger in some situations where 3/1 would have enabled
    avoiding holes. 5/3 looks bad if the next roll is 42 or 41 where we miss the 5 point stack.

    ***My play is 3/1.***
    How likely am I to be correct?
    If a set theorist is selected at random, what is the probability that this mathematician prefers models of ZFC where CH is false
    to models of ZFC where CH is true?
    If we call that probability p, then p is my estimated probability that I am solving this quiz correctly.

    Paul

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  • From Timothy Chow@21:1/5 to All on Mon Jan 10 22:02:50 2022
    XGID=-BCBbCB-C-a-----abbcbb----:1:-1:1:62:0:0:0:0:10

    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 O O | +---+
    | O O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | X X |
    | X | | X X O X X X |
    | O X | | X X O X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 65 O: 132 X-O: 0-0
    Cube: 2, O own cube
    X to play 62

    Ripping up the board with 3/1 just "felt wrong" to me, so I didn't
    consider it seriously. But a blot on the 3pt isn't much of a liability;
    O isn't going to be breaking anchor any time soon, except to hit, and
    in that scenario X is probably doomed anyway. X's main task is just to
    move his checkers past O's anchor safely.

    It is natural to look first at immediate blotting rolls. Either way,
    61 blots. After 8/2 5/3, the only other blotting roll is 64, but it
    leaves *two* blots; after 8/2 3/1, 64 leaves just one blot, but 44 also
    blots. This comparison is perhaps not entirely clear.

    I believe that the key point to notice is that 8/2 5/3 leads to more
    blotting rolls later. For example, suppose X rolls 62 63 52 or 53.
    X brings both checkers in safely for now, but has five checkers
    somewhat awkwardly placed in front of O's anchor. Similarly if X
    blots with 61 and O misses, X's cleanup will tend to be easier with
    a spare on his 5pt.

    1. Rollout¹ 8/2 3/1 eq:+0.690
    Player: 82.86% (G:9.83% B:0.03%)
    Opponent: 17.14% (G:2.27% B:0.08%)
    Confidence: ±0.004 (+0.686..+0.694) - [100.0%]

    2. Rollout¹ 8/2 5/3 eq:+0.648 (-0.042)
    Player: 80.38% (G:11.05% B:0.02%)
    Opponent: 19.62% (G:2.07% B:0.07%)
    Confidence: ±0.004 (+0.644..+0.652) - [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

    ---
    Tim Chow

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Mon Jan 10 22:16:12 2022
    On 1/9/2022 5:50 PM, peps...@gmail.com wrote:
    The only alternative is 5/3 but then why would Tim post about that, particularly when there's a shortage
    of rigorous beginners' accounts on using forcing to prove independence results in set theory? I'm sure Tim's notes
    could be improved. (I'm reading Weaver at the moment (Nik not Tom).)

    If you're not aware of it, Scott Aaronson made an interesting blog post
    on this topic some time ago.

    https://scottaaronson.blog/?p=4974

    Unfortunately, despite highly positive feedback from his readers, he has
    not been motivated to write any followup posts.

    I have thought about writing a sequel to my "beginner's guide," but I
    have not yet reached a point where I feel I have enough additional
    insights to merit another paper.

    If a set theorist is selected at random, what is the probability that this mathematician prefers models of ZFC where CH is false
    to models of ZFC where CH is true?

    In case you don't already know, there was an interesting article in
    Quanta on this topic last year.

    https://www.quantamagazine.org/how-many-numbers-exist-infinity-proof-moves-math-closer-to-an-answer-20210715/

    ---
    Tim Chow

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  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Tue Jan 11 05:13:44 2022
    On Tuesday, January 11, 2022 at 3:02:53 AM UTC, Tim Chow wrote:
    XGID=-BCBbCB-C-a-----abbcbb----:1:-1:1:62:0:0:0:0:10

    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 O O | +---+
    | O O | | O O O | | 2 |
    | | | O | +---+
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | |
    | X | | X X |
    | X | | X X O X X X |
    | O X | | X X O X X X |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 65 O: 132 X-O: 0-0
    Cube: 2, O own cube
    X to play 62
    Ripping up the board with 3/1 just "felt wrong" to me, so I didn't
    consider it seriously. But a blot on the 3pt isn't much of a liability;
    O isn't going to be breaking anchor any time soon, except to hit, and
    in that scenario X is probably doomed anyway. X's main task is just to
    move his checkers past O's anchor safely.

    It is natural to look first at immediate blotting rolls. Either way,
    61 blots. After 8/2 5/3, the only other blotting roll is 64, but it
    leaves *two* blots; after 8/2 3/1, 64 leaves just one blot, but 44 also blots. This comparison is perhaps not entirely clear.

    I believe that the key point to notice is that 8/2 5/3 leads to more blotting rolls later. For example, suppose X rolls 62 63 52 or 53.
    X brings both checkers in safely for now, but has five checkers
    somewhat awkwardly placed in front of O's anchor. Similarly if X
    blots with 61 and O misses, X's cleanup will tend to be easier with
    a spare on his 5pt.

    1. Rollout¹ 8/2 3/1 eq:+0.690
    Player: 82.86% (G:9.83% B:0.03%)
    Opponent: 17.14% (G:2.27% B:0.08%)
    Confidence: ±0.004 (+0.686..+0.694) - [100.0%]

    2. Rollout¹ 8/2 5/3 eq:+0.648 (-0.042)
    Player: 80.38% (G:11.05% B:0.02%)
    Opponent: 19.62% (G:2.07% B:0.07%)
    Confidence: ±0.004 (+0.644..+0.652) - [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

    Very similar to my argument for 3/1 but I got some of the details wrong -- for example, I didn't notice that 3/1 blots with 44,
    though I'm sure I would have played it anyway.

    Paul

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  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Tue Jan 11 05:50:09 2022
    On Tuesday, January 11, 2022 at 3:16:16 AM UTC, Tim Chow wrote:
    On 1/9/2022 5:50 PM, peps...@gmail.com wrote:
    The only alternative is 5/3 but then why would Tim post about that, particularly when there's a shortage
    of rigorous beginners' accounts on using forcing to prove independence results in set theory? I'm sure Tim's notes
    could be improved. (I'm reading Weaver at the moment (Nik not Tom).)
    If you're not aware of it, Scott Aaronson made an interesting blog post
    on this topic some time ago.

    https://scottaaronson.blog/?p=4974

    Unfortunately, despite highly positive feedback from his readers, he has
    not been motivated to write any followup posts.

    I have thought about writing a sequel to my "beginner's guide," but I
    have not yet reached a point where I feel I have enough additional
    insights to merit another paper.
    If a set theorist is selected at random, what is the probability that this mathematician prefers models of ZFC where CH is false
    to models of ZFC where CH is true?
    In case you don't already know, there was an interesting article in
    Quanta on this topic last year.

    https://www.quantamagazine.org/how-many-numbers-exist-infinity-proof-moves-math-closer-to-an-answer-20210715/

    I intended a jokey way of saying I was (rightly, I think) very confident in my 3/1 choice. Firstly, there's only one way to be wrong.
    Secondly, it wouldn't be an interesting quiz otherwise. Thirdly, 3/1 is solidly motivated (as I tried to show).
    I thought that all knowledgeable people rejected CH and intended the probability to be very close to 1.
    After briefly looking through the Quanta magazine article, I'm less sure (about what set theorists think).
    Thank you very much for these references. I wasn't aware of them before.
    It's a pity David Ullrich has stopped posting here, because he'd be interested for sure.
    If someone knows David (I don't), then maybe they could contact him about this. As far as I know, Tim and David are the only research maths people [who have been] involved with rgb.
    Note that I'm not saying at all that Tim and David are the only research maths people involved with rgb.
    The "As far as I know" caveat is a crucial qualifier.

    I think the Quanta magazine article is much better than usual for pop maths article, despite the topic being so difficult.
    The article which Quanta discusses is available here: https://ivv5hpp.uni-muenster.de/u/rds/MM_implies_star_final_version_March_18_2021.pdf

    Paul

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  • From Timothy Chow@21:1/5 to Timothy Chow on Tue Jan 11 09:20:36 2022
    On 1/11/2022 9:16 AM, Timothy Chow wrote:
    On 1/11/2022 8:50 AM, peps...@gmail.com wrote
    As far as I know, Tim and David are the only research maths people
    [who have been] involved with rgb.
    Note that I'm not saying at all that Tim and David are the only
    research maths people involved with rgb.
    The "As far as I know" caveat is a crucial qualifier.

    Douglas Zare used to be involved in r.g.b. and used to be a research mathematician, but I don't think he does math research any more.

    I forgot Philippe Michel, who is still occasionally active here.

    ---
    Tim Chow

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Tue Jan 11 09:16:26 2022
    On 1/11/2022 8:50 AM, peps...@gmail.com wrote
    I thought that all knowledgeable people rejected CH and intended the probability to be very close to 1.
    After briefly looking through the Quanta magazine article, I'm less sure (about what set theorists think).

    I don't know either, but I believe that a sizable percentage of set
    theorists either have no opinion, or think it's a non-question (meaning
    either that there is no fact of the matter about whether CH is true or
    false, or if there is, we'll never be able to *settle* the question).

    Among those who do think it's a meaningful question and that it could
    be settled, I don't think very many believe that it *has* been settled.
    That's kind of what the Quanta article is about. Most people in this
    camp agree that either c = aleph_0 or c = aleph_2 but think there are
    arguments both ways.

    As far as I know, Tim and David are the only research maths people [who have been] involved with rgb.
    Note that I'm not saying at all that Tim and David are the only research maths people involved with rgb.
    The "As far as I know" caveat is a crucial qualifier.

    Douglas Zare used to be involved in r.g.b. and used to be a research mathematician, but I don't think he does math research any more.

    I think the Quanta magazine article is much better than usual for pop maths article, despite the topic being so difficult.

    I find this to be true of most Quanta articles on mathematics.

    ---
    Tim Chow

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  • From pepstein5@gmail.com@21:1/5 to Tim Chow on Tue Jan 11 08:34:56 2022
    On Tuesday, January 11, 2022 at 2:16:30 PM UTC, Tim Chow wrote:
    ... Most people in this
    camp agree that either c = aleph_0 or c = aleph_2 but think there are arguments both ways.
    ...

    Is this a typo? By "aleph_0", do you mean "aleph_1"?

    Paul

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  • From Timothy Chow@21:1/5 to peps...@gmail.com on Tue Jan 11 18:04:27 2022
    On 1/11/2022 11:34 AM, peps...@gmail.com wrote:
    On Tuesday, January 11, 2022 at 2:16:30 PM UTC, Tim Chow wrote:
    ... Most people in this
    camp agree that either c = aleph_0 or c = aleph_2 but think there are
    arguments both ways.
    ...

    Is this a typo? By "aleph_0", do you mean "aleph_1"?

    Yes, of course...sorry.

    ---
    Tim Chow

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