% Possibilities
suspect(ms-scarlet; colonel-mustard).
weapon(revolver; candle).
place(kitchen; hall; dining-room).

% One possibility only
1{murderer(X):suspect(X)}1.
1{weapon-of-crime(X):weapon(X)}1.
1{place-of-crime(X):place(X)}1.

% Card deduction
:- place(kitchen).
place(hall) :- murderer(colonel_mustard), not weapon(revolver).
weapon(candle).