proposition: Lemma filter_from_norm_nbhs x : @filter_from R _ [set x : R | 0 < x] (ball_norm x) = nbhs x.
proof: Proof. by rewrite -nbhs_nbhs_norm ball_normE. 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