| n ≤ # x ⊦ n = 0, sublist(0, n, x) = x.head ' + sublist(0, n -1, x.tail) |
n ≤ # x ⊦ firstn(n, x) = x.head ' + firstn(n - 1, x.tail), n = 0
Used simplifier rules: sublist-def: ⊦ sublist(m, n, x) = firstn(n, restn(m, x));%restN-zero: ⊦ restn(0, x) = x;% ⊦ n -1 = n - 1; (s)