| n ≤ # x0, dups(lastn(n, x0)), ∀ n0. n0 < # x0 → ¬ dups(lastn(n0, x0)) ⊦ a ∈ x0, dups(x0) |
Used simplifier rules: lastN-all: ⊦ n = # x → lastn(n, x) = x;%lels: ⊦ ¬ m < n ↔ n ≤ m; from specification nat%anti: ⊦ m ≤ n → (n ≤ m ↔ m = n); from specification nat Used terms: n