proposition: Lemma is_cvgVE f : lim (f @ F) != 0 -> cvg (f\^-1 @ F) = cvg (f @ F).
proof: Proof. move=> ?; apply/propeqP; split=> /is_cvgV; last exact. by rewrite inv_funK; apply; rewrite limV ?invr_eq0//. 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