1-mutually_exclusive(S1, S2) :-
    2    member(X, S1), member(X, S2). 
    3
    4mutually_exclusive(S1, S2) :-
    5    not -mutually_exclusive(S1, S2). 
    6
    7member(X1, [X2|_]) :- X1 #= X2.  
    8member(X, [_|R]) :- member(X, R). 
    9
   10?- mutually_exclusive([1,2], [3,4]).