∀ a, d, az. a ∈ ay0 ∧ unique_al(ay0 + (a × d)' + az) → a ∈ az, a ∈ p + ay0, unique_al((p + ay0) + (a × d)' + az) ⊦ a ∈ az
Used simplifier rules: empty: ⊦ ¬ a ∈ [];%assoclist freely generated by [], +;;