| i < 0, 0 < i0, abs(i) = abs(i0) ∨ abs(i0) < abs(i) ⊦ gcd(i, i0 - abs(i)) = gcd(abs(i), abs(i0)), i = 0 |
abs(i) = abs(i0), 0 < i0, i < 0 ⊦ gcd(i, i0 - abs(i)) = gcd(abs(i), abs(i0)), i = 0
0 < i0, i < 0, abs(i0) < abs(i) ⊦ gcd(i, i0 - abs(i)) = gcd(abs(i), abs(i0)), i = 0