fact: Definition coarse_in (r : gregion) (m : matte) := forall p q, r p -> halfg q = halfg p -> (q \in m) = (p \in m).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path order ssralg ssrnum ssrint div intdiv) fourcolor(grid)