proposition: Lemma continuity_pt_dnbhs f x : continuity_pt f x <-> forall eps, 0 < eps -> x^' (fun u => `|f x - f u| < eps).
proof: Proof. by rewrite continuity_pt_cvg' -filter_fromP cvg_ballP -filter_fromP. Qed.
imports: Rdefinitions Raxioms RIneq Rbasic_fun Zwf Epsilon FunctionalExtensionality Ranalysis1 Rsqrt_def Rtrigo1 Reals mathcomp(all_ssreflect ssralg poly mxpoly ssrnum) HB(structures) mathcomp(boolp classical_sets) reals signed topology