∀ key. ¬(∃ n. key = inodekey(n) ∧ n ∈ ns) ⊦ # ns = 0, ns = ∅
Used simplifier rules: keys-in: ⊦ key ∈ ns.keys ↔ (∃ n. key = inodekey(n) ∧ n ∈ ns);% ⊦ ¬ key ∈ ∅; (s)