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