| j1 < 0 ⊦ j1 = 0, j2 = 0, rational(i1, j1) + rational(i2, j2) = rational(i1 * j2 + j1 * i2, j1 * j2) |
⊦ j < 0 → rational(i, j) = rational(~ i, abs(j))
j1 < 0, j1 < 0 ⊦ j1 = 0, j2 = 0, rational(~ i1, abs(j1)) + rational(i2, j2) = rational(i1 * j2 + j1 * i2, j1 * j2)
Used terms: j1, i1