proposition: Fact gcompr_face_subproof v : predC (gcomp z) (face (val v)).
proof: Proof. by rewrite /= -(glink1r (glinkF _)) (valP v). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry jordan color coloring)