[Retros] No occupied white square

Noam Elkies elkies at math.harvard.edu
Fri Dec 6 12:28:26 EST 2013

Francois Labelle <flab at wismuth.com> writes:

> My computer found a unique proof game in 10.0 moves with 21 men all on

> white squares, and another unique proof game in 10.0 moves with 21 men

> all on black squares. A lovely pair of problems! Both are confirmed by

> Euclide.


> Looks like this is computer territory. Sorry Unto!


> Now I'd like to know if Unto is still going to publish his 11.0-move

> problem in a magazine, and whether I should publish my 2 problems in a

> magazine...

I don't see why not. Heinonen's problem was still the first of its kind
(albeit by only a few days thanks to near-instantaneous global communication);
and the mechanism is probably different. And you've already published some
of your earlier computer discoveries in problem magazines, so why not these?


P.S. Is it feasible to compute how many such proof games there are in
10.5 or even 11.0 and beyond? It would be interesting to see what
the range of possibilities is (and how much choice Heinonen had for
his 11.0-mover).

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