| ¬ rational(i0, j0) ≠ 0r, rational(i, j) / ~ rational(i0, j0) = ~ rational(i * j0, i0 * j), 0 < j, 0 < j0, i < 0, i0 < 0 ⊦ i = 0, rational(i, j) / rational(i0, j0) = rational(i * j0, j * i0), i0 = 0, ~ rational(i0, j0) = 0r, j = 0 |
rational(i0, j0) = 0r, rational(i, j) / ~ 0r = ~ rational(i * j0, i0 * j), 0 < j, 0 < j0, i < 0, i0 < 0 ⊦ i = 0, rational(i, j) / 0r = rational(i * j0, j * i0), i0 = 0, ~ 0r = 0r, j = 0