Definition ex_lim_seq_cauchy (u : nat -> R) :=
  forall eps : posreal, exists N : nat, forall n m,
    (N <= n)%nat -> (N <= m)%nat -> Rabs (u n - u m) < eps.

Lemma is_lim_seq_le_m_loc (u v : nat -> R) : eventually (fun n => v n <= u n) -> is_lim_seq u m_infty -> is_lim_seq v m_infty.