proposition: Lemma le_ereal_ball x : {homo ereal_ball x : e e' / (e <= e')%R >-> e `<=` e'}.
proof: Proof. by move=> e e' ee' y; rewrite /ereal_ball => /lt_le_trans; exact. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(fsbigop cardinality set_interval) reals signed topology constructive_ereal