| n ≠ 0, a = x0[n -1], n ≤ # x0, ∀ m0, n0. x0[m0] = x0[n0] ∧ n0 < # x0 ∧ m0 < # x0 → m0 = n0 ∨ x0 = [] ⊦ 0 = n, a ∈ x0, dups(x0) |
n ≤ # x0, ∀ m0, n0. x0[m0] = x0[n0] ∧ n0 < # x0 ∧ m0 < # x0 → m0 = n0 ∨ x0 = [] ⊦ n = 0, dups(x0), x0[n - 1] ∈ x0
Used simplifier rules: pred-03: ⊦ n -1 = n - 1; from specification nat