proposition: Lemma iter_split_ent j : entourage (iter j split_sym (E `&` E^-1)).
proof: Proof. by elim: j => [|i IH]; exact: filterI. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed