max(m + 1, n) ≤ n0, ∀ n0. n0 ∈ ns → n0 < n, n0 = m ∨ n0 ∈ ns ⊦
Used simplifier rules: ⊦ m < n ↔ ¬ n ≤ m; (ss)% ⊦ n ∈ ns ++ n0 ↔ n = n0 ∨ n ∈ ns; (s)