j ≠ 0 ∨ j0 ≠ 0, j * j = i * j0 * j0 ⊦ ∃ i0. i = i0 * i0
∃ i0. j = i0 * i0, gcd(i, j0) = 1, i * i = j * j0 * j0, 0 < j0 ⊦ j0 = 0, ∃ i. j = i * i
Used terms: i, j0, j