| ⊦ i1 ≠ 0 ∧ i2 ≠ 0 ∧ j1 ≠ 0 ∧ j2 ≠ 0 → ( rational(i1, j1) = rational(i2, j2) ↔ abs(i1) / gcd(i1, j1) = abs(i2) / gcd(i2, j2) ∧ abs(j1) / gcd(i1, j1) = abs(j2) / gcd(i2, j2) ∧ ( (0 < i1 ∧ 0 < j1 ∨ i1 < 0 ∧ j1 < 0) ∧ (0 < i2 ∧ 0 < j2 ∨ i2 < 0 ∧ j2 < 0) ∨ (0 < i1 ∧ j1 < 0 ∨ i1 < 0 ∧ 0 < j1) ∧ (0 < i2 ∧ j2 < 0 ∨ i2 < 0 ∧ 0 < j2))) |