⊦ s ∩ s0 = ∅ ↔ (∀ a. ¬ a ∈ s ∨ ¬ a ∈ s0)
∀ a. ¬ a ∈ list2set(x) ∨ ¬ a ∈ s, a ∈ s, a ∈ x ⊦ s = ∅, # s = 0
Used terms: s, list2set(x)