⊦ i * j = j * i
j0 < j, 0 < j, 0 ≤ j0, 0 ≤ i0 ⊦ j = 0, i0 = 2 * i0 / 2 + (i0 * j + j0 < (1 + 2 * i0 / 2) * j ⊃ 0;1)
Used terms: 1 + 2 * i0 / 2, j