You need some Stern-Brocot action for this one. On Sun, Apr 17, 2016 at 6:40 AM, James Propp <jamespropp@gmail.com> wrote:
Keith Lynch was the first to solve this puzzle (or at least the first to email me a solution).
Rich Schroeppel pointed out that the restriction to [0,1] is unnecessary.
It's now Sunday where I am, so Keith and others may post freely.
Jim Propp
On Friday, April 15, 2016, James Propp <jamespropp@gmail.com> wrote:
There's a unique way to 3-color the rationals in [0,1] using the colors red, blue, and green so that 0 is red, 1 is blue, and the fractions a/b, c/d, and (a+c)/(b+d) all have distinct colors whenever ad-bc=1.
Puzzle (no spoilers till Sunday please!): What color is 355/113?
Jim Propp
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