| ay = p + ax0 ⊦ unique_al(ay) ↔ ay = [] ∨ ¬ p.1 ∈ ax0 ∧ unique_al(ax0), ay = [] |
⊦ unique_al(p ' + ax0) ↔ ¬ p.1 ∈ ax0 ∧ unique_al(ax0)
Used simplifier rules: a: ⊦ (ax + ax0) + ax1 = ax + ax0 + ax1; from specification list[assoclist]% ⊦ p ' + ax ≠ []; (s)% ⊦ p + ax = p ' + ax; (s)