proposition: Lemma relabel_merge F r: relabel (merge F r) ≃ merge (relabel F) r.
proof: Proof. Iso bij_id bij_id xpred0. split=>//= v. elim/big_rec2 : _ => [|i y1 y2 _ ->]; by [rewrite ?Hfvmon2|symmetry]. Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)