proposition: Lemma eq_pmap_trans n k1 k2 k3 : eq_pmap n k1 k2 -> eq_pmap n k2 k3 -> eq_pmap n k1 k3.
proof: Proof. by move=> Ek12 Ek23; split=> [/Ek12/Ek23 | /Ek23/Ek12]; apply. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path ssralg ssrint) fourcolor(real realplane realsyntax realprop) fourcolor(grid approx)