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EIGHT_QUEENS

                                             September 12, 2012
                                             February  04, 2015

  Once upon a time, while studying engineering
  at a state university in New York, a friend--
  a guy I'd known since high school-- came over        BIG_WALTER
  to my dorm room, and began talking about
  something that he'd been working on all night
  with some friends of his (bright guys, all).
  It was a puzzle I've since come to know as
  "the eight queens problem":

  Can you place eight queens on a chessboard
  so that none of them are attacking each
  other?

     They had gone at this problem without any
     success, tackling it in various ways:
     Intuition, reason, trial and error...

     They tried starting with the presumption
     that a solution would have some sort of
     symmetric, regular pattern to it, but
     didn't get anywhere with that.

     They could find some solutions with
     only 7-queens, but couldn't find any
     way to modify them to become an 8-queen
     solution.


     He was showing us one of these
     "almost worked" configurations:
     I walked up to it, moved a few                 SOLUTION_NINE
     pieces around, and had a working
     solution, and a symmetric one at
     that.

        He was suitably astonished at
        this point, but then I cleared            He then phoned his friends,
        the board, and set up the pieces          telling them what I'd come
        in yet another solution, this             up with... and later, the
        time without any obvious symmetry.        next day I think, he
                                                  started going on about this
            So, that was a moment                 again, talking about how
            where I was being                     hard they'd worked on it
            pretty brilliant, if                  and how my two solutions
            I do say so myself,                   had to be just luck.
            but I can't replicate
            the achievement, and                      (I never get credit
            can't produce such                        for "genius", just
            flashes of insight                        general weirdness.)
            on demand.
                                                  I pulled out the
            And-- the reason I                    chessboard again
            bring this up-- I                     to see if I could do
            certainly can't tell                  it again, and failed.
            you what I was doing.
            I have many thoughts
            where I can trace out
            a laborious chain of
            how I got there, but
            these cases of sudden,
            intutive leaps don't       KHANEMAN_SLOWLY
            fit that category.

                  This "eight queens"
                  incident isn't the only     And needless to say,
                  such case, but it's a       it's not that hard to
                  nice, unambiquous one.      find converse examples
                                              where I could've sworn
                                              I was right, but...



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