| unique_al(ax), ∀ a. a ∈ ax → a ∈ ay ⊦ # ax ≤ # ay |
# ay < # ax, unique_al(ax.tail), ∀ a. a ∈ ax → a ∈ ay ⊦ ax = [], ax.head.1 ∈ ax.tail
Used simplifier rules: k-unique-r: ⊦ unique_al(ay) ↔ ay = [] ∨ ¬ ay.head.1 ∈ ay.tail ∧ unique_al(ay.tail);% ⊦ # ax = 0 ↔ ax = []; (s)%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic% ⊦ m ≤ n ↔ ¬ n < m; (ss)