| ∀ ns0, n. # ns0 < # ns → true → (inodekey(n) ∈ ns0.keys ↔ n ∈ ns0) ⊦ # ns = 0, inodekey(n) ∈ ns.keys ↔ n ∈ ns, ns = ∅ |
⊦ ns = ns0 ↔ (∀ n. n ∈ ns ↔ n ∈ ns0)
∀ ns0, n. # ns0 < # ns → true → (inodekey(n) ∈ ns0.keys ↔ n ∈ ns0) ⊦ # ns = 0, inodekey(n) ∈ ns.keys ↔ n ∈ ns, ∀ n. n ∈ ns ↔ n ∈ ∅
Used terms: ∅, ns