| ∃ i0. j = i0 * i0, gcd(i, j0) = 1, i * i = j * j0 * j0, 0 < j0 ⊦ j0 = 0, ∃ i. j = i * i |
gcd(i, j0) = 1, abs(i) = abs(i0) * j0, 0 < j0 ⊦ j0 = 0, ∃ i1. abs(i0) = abs(i1)
Used simplifier rules: ⊦ i * j = j * i;% ⊦ i * j * j0 = (i * j) * j0;% ⊦ 0 < j → abs(j) = j;% ⊦ abs(i * j) = abs(i) * abs(j);% ⊦ i * i = j * j ↔ abs(i) = abs(j);