| m ≤ # x0, n ≤ # x0, ∀ m, n, a. m < # x0 ∧ n < # x0 → (a ∈ x0[m, x0[n]][n, x0[m]] ↔ a ∈ x0) ⊦ n = 0, a ∈ (a0 ' + x0)[m, x0[n - 1]][n, (a0 ' + x0)[m]] ↔ a = a0 ∨ a ∈ x0 |
n = m0 + 1, m ≤ # x0, n ≤ # x0, ∀ m, n, a. m < # x0 ∧ n < # x0 → (a ∈ x0[m, x0[n]][n, x0[m]] ↔ a ∈ x0) ⊦ n = 0, a ∈ (a0 ' + x0)[m, x0[m0]][n, (a0 ' + x0)[m]] ↔ a = a0 ∨ a ∈ x0
Used simplifier rules: n ≠ 0 ⊦ m = n - 1 ↔ n = m + 1; (elim) Used terms: n, m1