gcd(i, j) + gcd(i0, j0) = 0, 0 < gcd(i, j) ⊦ gcd(i, j) = 0
Used simplifier rules: forward-le-05: ⊦ i < j ∧ 0 ≤ i → 0 < j; (forward) from specification int-abs% ⊦ i ≠ j → (i ≤ j ↔ i < j); (s)