proposition: Lemma is_lim_minus' (f g : R -> R) (x : Rbar) (lf lg : R) : is_lim f x lf -> is_lim g x lg -> is_lim (fun y => f y - g y) x (lf - lg).
proof: Proof. intros Hf Hg. eapply is_lim_minus ; try eassumption. by []. Qed.
imports: Coq(Reals ssreflect) Rcomplements Rbar Hierarchy Compactness Lim_seq