| x0[m -1] = (a ' + x0)[n], n ≤ # x0, m ≤ # x0, ∀ m0, n0. x0[m0] = x0[n0] ∧ m0 < # x0 ∧ n0 < # x0 → m0 = n0 ∨ x0 = [] ⊦ m = n, m = 0, dups(x0), a ∈ x0 |
x0[m - 1] = (a ' + x0)[n], m ≤ # x0, n ≤ # x0, ∀ m0, n0. x0[m0] = x0[n0] ∧ m0 < # x0 ∧ n0 < # x0 → m0 = n0 ∨ x0 = [] ⊦ m = 0, m = n, dups(x0), a ∈ x0
Used simplifier rules: ⊦ n -1 = n - 1; (s)