proposition: Lemma ball_inj x y r s : 0 < r -> ball x r = ball y s -> x = y /\ r = s.
proof: Proof. by move=> r0 xrys; split; [exact: (ball_inj_center r0 xrys)| exact: (ball_inj_radius r0 xrys)]. 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