| m0 < # x, m0 < n, n ≤ # x, ∀ n, x. n ≤ # x ∧ m0 ≤ n ∧ m0 ≤ # x → firstn(m0, firstn(n, x)) = firstn(m0, x) ⊦ firstn(n, x).head ' + firstn(m0, firstn(n, x).tail) = x.head ' + firstn(m0, x.tail), x = [] |
x = a + y, m0 < n, m0 < # x, n ≤ # x, ∀ n, x. n ≤ # x ∧ m0 ≤ n ∧ m0 ≤ # x → firstn(m0, firstn(n, x)) = firstn(m0, x) ⊦ firstn(n, x).head ' + firstn(m0, firstn(n, x).tail) = a ' + firstn(m0, y), x = []
Used simplifier rules: x ≠ [] ⊦ a = x.head ∧ y = x.tail ↔ x = a + y; (elim) Used terms: x, a, y