n0 < n ⊦ gcd(0 * n + n0, n) = gcd(n, n0)
∀ n0, n. n0 < n → gcd(m * n + n0, n) = gcd(n, n0), n0 < n ⊦ gcd(m +1 * n + n0, n) = gcd(n, n0)
Used simplifier rules: nat freely generated by 0, +1;;