proposition: Lemma union_merge_lE' (x: F+G): union_merge_l^-1 (\pi x) = match x with inl y => @unl _ _ (merge_seq F l) _ (\pi y) | inr y => unr y end.
proof: Proof. by rewrite /=quot_sameE' union_quot_lE'. Qed.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)