∀ a, d. unique_al(ax0) ∧ a × d ∈ ax0 → ax0[a] = d ⊦ unique_al(p + ax0) ∧ a × d ∈ p + ax0 → (p + ax0)[a] = d
Used simplifier rules: unique-e: ⊦ unique_al([]);%assoclist freely generated by [], +;;% ⊦ ¬ p ∈ [];