proposition: Lemma endpoint_iso' F G (h: iso F G) b e: endpoint b (h.e^-1 e) = h^-1 (endpoint (h.d (h.e^-1 e) (+) b) e).
proof: Proof. apply (endpoint_iso (iso_sym h)). Qed.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)