proposition: Lemma split_ent_subset (E : set (M * M)) : entourage E -> split_ent E `<=` E.
proof: Proof. move=> entE; case=> x y splitxy; apply: subset_split_ent => //; exists y => //. by apply: entourage_refl; exact: entourage_split_ent. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed