hat da jemand eine ahnung?
sum(L,S)
% S is the sum of the integers in list L, e.g. sum([2,3,4],9).
% Use the built-in relation plus(X,Y,Z), e.g. plus(1,2,3).
double(X,Y) % Each element in list X occures exactly twice in list Y
% E.g. double([1,2,3],[1,1,2,2,3,3])
interval(X,Y,L)
% L is a list whose elements are integers between X and Y.
% E.g. interval(4,7,[4,5,6,7])
numbers(L)
% L is a list whose elements only include the single integers
% 0,1,…9
