0 ≤ i ⊦ gcd(i, i0 + i) = gcd(i0 + i, i0), 0 < i ∧ i < i0 + i
Used simplifier rules: forward-le-01: ⊦ i ≤ j ∧ 0 ≤ i → 0 ≤ j; (forward) from specification int-abs% ⊦ i < j ↔ ¬ j ≤ i; (ss)