| 0 ≤ j, 0 < i0, ∀ j. 0 ≤ i0 ∧ 0 ≤ j → i→n(i0) + i→n(j) = i→n(i0 + j) ⊦ i→n(i0 - 1) + i→n(j) = i→n(j + i0 - 1) |
i0 = i1 + 1, 0 ≤ j, 0 < i0, ∀ j. 0 ≤ i0 ∧ 0 ≤ j → i→n(i0) + i→n(j) = i→n(i0 + j) ⊦ i→n(i1) + i→n(j) = i→n(j + i0 - 1)
Used simplifier rules: ⊦ i0 = i - j ↔ i = i0 + j; (elim) Used terms: i0, 1, i