proposition: Lemma closed_ballxx (R : numDomainType) (V : pseudoMetricType R) (x : V) (e : R) : 0 < e -> closed_ball x e x.
proof: Proof. by move=> ?; exact/subset_closure/ballxx. 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