proposition: Lemma gcompF (G : hypermap) : subrel (cface : rel G) gcomp.
proof: Proof. by apply: connect_sub => u v /= A; apply: connect1; rewrite /glink/= A. Qed.
imports: mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij) fourcolor(hypermap geometry cfmap jordan color coloring combinatorial4ct) fourcolor(walkup)