⊦ i < j ↔ ¬(i = j ∨ j < i)
i < 0, 0 < i0, abs(i) = abs(i0) ∨ abs(i0) < abs(i) ⊦ gcd(i, i0 - abs(i)) = gcd(abs(i), abs(i0)), i = 0
Used terms: abs(i0), abs(i)