proposition: Lemma vlabel_iso' F G (h: iso F G) v: vlabel (h^-1 v) ≡ vlabel v.
proof: Proof. apply (vlabel_iso (iso_sym h)). Qed.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)