| m0 < n, n ≤ # y + 1, m0 ≤ # y, ∀ n, x. m0 ≤ n ∧ n ≤ # x ∧ m0 ≤ # x → firstn(m0, firstn(n, x)) = firstn(m0, x) ⊦ n = 0, firstn(m0, firstn(n - 1, y)) = firstn(m0, y) |
n = m + 1, m0 < n, n ≤ # y + 1, m0 ≤ # y, ∀ n, x. m0 ≤ n ∧ n ≤ # x ∧ m0 ≤ # x → firstn(m0, firstn(n, x)) = firstn(m0, x) ⊦ n = 0, firstn(m0, firstn(m, y)) = firstn(m0, y)
Used simplifier rules: n ≠ 0 ⊦ m = n - 1 ↔ n = m + 1; (elim) Used terms: n, m