∀ ns0, n, m. # ns0 < # ns → true → (n ∈ below(ns0, m) ↔ n ∈ ns0 ∧ n < m) ⊦ n ∈ below(ns, m) ↔ n ∈ ns ∧ n < m
Used simplifier rules: <; (wellfounded) Used terms: # ns