max∞(np) = ⌜n1⌝ , n1 < n, np(n1), np(n), ∀ m. np(m) → ¬ n1 < m ⊦
Used simplifier rules: ⊦ m < n → n ≠ 0; (s)%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic