⊦ ¬ dups(x) ∧ n < # x → (a ∈ x -p n ↔ a ≠ x[n] ∧ a ∈ x)
Used simplifier rules: rmtoobigpos: ⊦ # x ≤ n → x -p n = x;% ⊦ m < n ↔ ¬ n ≤ m; (ss) Used terms: n1, x0, a