| 0 < j1, 0 < j0, 0 < j ⊦ j = 0, j0 = 0, rational(i * j0 + j * i0, j * j0) + rational(i1, j1) = rational(i, j) + rational(i0, j0) + rational(i1, j1) |
⊦ j1 ≠ 0 ∧ j2 ≠ 0 → rational(i1, j1) + rational(i2, j2) = rational(i1 * j2 + j1 * i2, j1 * j2)
j0 ≠ 0 ∧ j1 ≠ 0, 0 < j1, 0 < j0, 0 < j ⊦ j = 0, j0 = 0, rational(i * j0 + j * i0, j * j0) + rational(i1, j1) = rational(i, j) + rational(i0 * j1 + j0 * i1, j0 * j1)
Used terms: j1, i1, j0, i0