| a ∈ x0 -1l n1, ∀ n0. ¬ dups(x0 -1l n0) ⊦ dups(x0 -1l n1), a ∈ x0, dups(x0) |
⊦ ¬ dups(x) ∧ n < # x → (a ∈ x -1l n ↔ a ≠ x[n] ∧ a ∈ x)
Used simplifier rules: rmtoobigpos: ⊦ # x ≤ n → x -1l n = x;%lels: ⊦ ¬ m < n ↔ n ≤ m; from specification nat Used terms: n1, x0, a