# ar ≤ m, ∀ n. n = m ∨ n ∈ nx0 → n < # ar, ∀ ar. nx0 < # ar ↔ (∀ n. n ∈ nx0 → n < # ar) ⊦
Used simplifier rules: ⊦ m < n ↔ ¬ n ≤ m; (ss)