m * n ≤ m + 1, m ≤ n ⊦ n * n ≤ m + 1 ↔ n ≤ 1 ∧ m ≤ 1
m ≤ n ⊦ m * n ≤ m + 1, n * n ≤ m + 1 ↔ n ≤ 1 ∧ m ≤ 1
Used formulas: m * n ≤ m + 1