Require Export Coq.Arith.Wf_nat.

Lemma le_case_lt {n : nat} {m : nat} (H_le : m <= n) (phi : m <= S n -> Prop)
(phi_lt : forall H_le' : m <= n, phi (@le_S m n H_le'))
: forall H_lt : m <= S n, phi H_lt.