⊦ as ⊆ as0 ↔ (∀ adr. adr ∈ as → adr ∈ as0)
as1 ∩ as3 ⊆ as ⊦ (∀ adr. adr ∈ (as0 ∪ (as1 \ as2)) ∩ as3 → adr ∈ as) ↔ as0 ∩ as3 ⊆ as
Used terms: as, (as0 ∪ (as1 \ as2)) ∩ as3