fact: Definition skip (x : T) : T := match @idP [exists n : 'I_(order f (f x)), iter n.+1 f x \in a] with | ReflectT E => iter (ex_minn (skip_proof E)).+1 f x | ReflectF _ => x end.
imports: mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij) fourcolor(hypermap geometry cfmap jordan color coloring combinatorial4ct) fourcolor(walkup)