| ints0 -1l i ≠ [], i < max(i0 ' + ints0), ∀ i. i < max(ints0) → max(ints0 -1l i) = max(ints0) ⊦ i = i0, max(i0, max(ints0 -1l i)) = max(i0 ' + ints0) |
i < max(i0 ' + ints0), ∀ i. i < max(ints0) → max(ints0 -1l i) = max(ints0) ⊦ ints0 -1l i = [], max(i0, max(ints0 -1l i)) = max(i0 ' + ints0), i = i0