| j < 0 ⊦ i = 0, j = 0, rational(i, j).num + rational(~ i, j).num = 0 |
⊦ 0 < i ∧ j < 0 → rational(i, j).num = ~(i / gcd(i, j))
¬(0 < i ∧ j < 0), j < 0 ⊦ i = 0, j = 0, rational(i, j).num + rational(~ i, j).num = 0
0 < i ∧ j < 0, j < 0 ⊦ i = 0, j = 0, ~(i / gcd(i, j)) + rational(~ i, j).num = 0
Used terms: j, i