proposition: Lemma scale_ball1 A : is_ball A -> 1 *` A = A.
proof: Proof. by move=> Aball; rewrite /scale_ball Aball mul1r; move/eqP in Aball. 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