?- reverse([4, 3, 2, 1], List), length(List, Lenght). List = [1, 2, 3, 4] Lenght = 4 Yes ?- numlist(1, 4, [1, 2, 3, 4]). Yes ?- reverse([4, 3, 2, 1], List), length(List, Lenght), numlist(1, Length, List). No