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