| 0 ≤ j, 0 ≤ i0, ∀ j0. 0 ≤ j0 → i→n(i0) * i→n(j0) = i→n(i0 * j0) ⊦ i→n(j) * i→n(i0) + i→n(j) = i→n((i0 + 1) * j) |
⊦ (i + 1) * j = i * j + j
0 ≤ j, 0 ≤ i0, ∀ j0. 0 ≤ j0 → i→n(i0) * i→n(j0) = i→n(i0 * j0) ⊦ i→n(j) * i→n(i0) + i→n(j) = i→n(i0 * j + j)
Used terms: j, i0