proposition: Lemma merge_merge_seqE (x: F): merge_merge_seq (\pi (\pi x)) = \pi x.
proof: Proof. by rewrite /=merge_mergeE merge_same'E. Qed.
imports: Coq(Morphisms RelationClasses) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij) GraphTheory(equiv digraph setoid_bigop structures)