proposition: Lemma ball_norm_le x (e1 e2 : R) : e1 <= e2 -> ball_norm x e1 `<=` ball_norm x e2.
proof: Proof. by move=> e1e2 y /lt_le_trans; apply. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrint ssrnum finmap matrix) mathcomp(rat interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality set_interval Rstruct) ereal reals signed topology prodnormedzmodule