# s0 = 1, a0 ∈ s0, a ∈ s0, b ∈ s0, ∀ b0, a1. b0 ∈ s0 ∧ a1 ∈ s0 → a1 = b0 ⊦ a = b
Used simplifier rules: eq: ⊦ a ∈ s → s ++ a = s;