likes(tom,beer).
likes(tom,cider).
likes(bill,cider).
likes(dick,beer).
likes(harry,beer).
likes(jan,cider).

% setof(X, likes(X,Y), S).
% bagof(X, likes(X,Y), S).
% findall(X, likes(X,Y), S).
% setof(X, Y^likes(X,Y), S).
%    setof(X,likes(X,_), S).
% bagof(X, Y^likes(X,Y), S).
%    bagof(X,likes(X,_), S).

% setof((Y,S),setof(X,likes(X,Y),S),SS).