| n ≤ n2, n2 ≤ # x, n + n1 ≤ n2, n + n1 ≤ # x, n ≤ # x ⊦ firstn(n1, firstn(n2 - n, restn(n, x))) = firstn(n1, restn(n, x)) |
n2 = n0 + n, n ≤ n2, n2 ≤ # x, n + n1 ≤ n2, n + n1 ≤ # x, n ≤ # x ⊦ firstn(n1, firstn(n0, restn(n, x))) = firstn(n1, restn(n, x))
Used simplifier rules: n ≤ m ⊦ n0 = m - n ↔ m = n0 + n; (elim) Used terms: n2, n, n0