fact: Fixpoint prove_leq n m : M (n < m) := match n, m with | 0, S _ => M.ret (lt_0_S _) | S n', S m' => H <- prove_leq n' m'; M.ret (succ_lt_mono_lr _ _ H) | _, _ => M.failwith "n not < m" end.
imports: Mtac2.Mtac2 Vector Lia