% THe problem of after lunch drinks.
run:-problem(Anne,Betty,Cindy).
drink(X):- X=tea; X=coffee.
problem(Anne, Betty, Cindy):- drink(Anne), drink(Betty), drink(Cindy),
	fact1(Anne, Betty, Cindy),
	fact2(Anne, Betty, Cindy),
	fact3(Anne, Betty, Cindy),
	print(anne=Anne), write(', '),
	print(betty=Betty),write(', '),
	print(cindy=Cindy),
	nl,
	fail.

fact1(A,B,C):- A=tea; (B=C).
fact2(A,B,C):- B=tea; (A\==C).
fact3(A,B,C):- C=coffee; (A=B).