#(s0 ++ a0) = 1, b ∈ s0 ++ a0, a ∈ s0 ++ a0, ∀ a, b. # s0 = 1 ∧ a ∈ s0 ∧ b ∈ s0 → a = b ⊦ a = b
Used simplifier rules: gen: ⊦ ;%Size-empty: ⊦ # ∅ = 0;