| j * j = i * j0 * j0, j < i, j < 0, 0 < i, j + 1 < i ⊦ j = 0, ∃ i0. i = i0 * i0 |
0 < i, 0 < j, 0 < j0, j * j = i * j0 * j0 ⊦ ∃ i0. i = i0 * i0
j * j = i * j0 * j0, j < i, j < 0, 0 < i, j + 1 < i ⊦ 0 < ~ j ∧ 0 < j0 ∧ ~ j * ~ j = i * j0 * j0, j = 0, ∃ i0. i = i0 * i0
Used terms: i, ~ j, j0