⊦ 0 < i → i→n(i) = i→n(i - 1) + 1
i0 < 0, 0 < ~ i0 ⊦ i→n(~ i0 - 1) + 1 = i→n(i0 + 1) + 1
Used simplifier rules: ⊦ 0 < ~ i ↔ i < 0; (s)% ⊦ i < j ↔ ¬ j ≤ i; (ss)% ⊦ i < j → (j ≤ i ↔ false); (as) Used terms: ~ i0