⊦ as ⊆ as0 ↔ (∀ adr. adr ∈ as → adr ∈ as0)
as0 ∩ as ⊆ as1 ⊦ as1 ⊆ as, ∀ adr. adr ∈ as0 ∩ as → adr ∈ as1 ∩ as
Used terms: as1 ∩ as, as0 ∩ as