proposition: Lemma closure_ball (c r : R) : closure (ball c r) = closed_ball c r.
proof: Proof. have [r0|r0] := leP r 0. by rewrite closed_ball0// ((ball0 _ _).2 r0) closure0. by rewrite (is_ball_closure (is_ball_ball _ _)) cpoint_ball// radius_ball ?ltW. 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