| m1 ≤ # x0, m2 + m ≤ m1, m2 + m ≤ # x0, ∀ n0, m0, n, m. n0 + m0 ≤ # x0 ∧ n + m ≤ m0 → firstn(m, restn(n, firstn(m0, restn(n0, x0)))) = firstn(m, restn(n0 + n, x0)) ⊦ firstn(m, restn(m2, firstn(m1, x0))) = firstn(m, restn(m2, x0)) |
m2 + m ≤ # x0, m2 + m ≤ m1, m1 ≤ # x0, m2 + m ≤ # x0 ∧ m1 + 0 ≤ m → firstn(0, restn(m1, firstn(m, restn(m2, x0)))) = firstn(0, restn(m2 + m1, x0)), ∀ n0, m0, n, m. n0 + m0 ≤ # x0 ∧ n + m ≤ m0 → firstn(m, restn(n, firstn(m0, restn(n0, x0)))) = firstn(m, restn(n0 + n, x0)) ⊦ firstn(m, restn(m2, firstn(m1, x0))) = firstn(m, restn(m2, x0))
Used terms: m2, m, m1, 0