proposition: Lemma pmap_std n1 n2 i : i < n1 -> in_pmap n2 'z_i -> in_pmap n1 'z_i.
proof: Proof. by move=> lt_i_n1 [_ _ /(map_cover m0P)[m0i _]]; exists i. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path ssralg ssrint) fourcolor(real realplane realsyntax realprop) fourcolor(grid approx)