[Retros] Happy New Year

Elkies, Noam elkies at math.harvard.edu
Fri Jan 1 01:20:35 EST 2021

It's that time of the year again:


  SPG-10.0; how many solutions? (C+; NDE 25.xii.2020)

This time Andrew Buchanan took a different approach:
see the last problem of


and this year "Leon Xray" posted on Facebook a different kind of
enumerative puzzle, with a nicely symmetrical diagram --


-- and a stipulation that makes it appropriate here, albeit barely:

  In how many ways can you add a White Queen and a Black Queen
to this diagram to obtain a legal position?

Wishing all a healthy and happy 2021,
--Noam D. Elkies

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