⊦ S ⊆ S0 ↔ (∀ x. S(x) → S0(x))
monotone(f), S ⊆ f(S) ⊦ ∀ x. S(x) → UN(λ S. S ⊆ f(S))(x)
Used terms: UN(λ S. S ⊆ f(S)), S