Consider the query 
	?- abba(X,Y), baba(X,Y).
with the database
	abba(1,1).			baba(1,2).
	abba(2,1).			baba(1,3).
	abba(3,2).			baba(2,3).
	abba(4,4).			baba(3,2).
	abba(5,6).			baba(4,4).

(a) Without using a computer, what are all the answers that you will get to the query, in order, as you keep on typing semicolons?
(b) Without using a computer, what does this query print out.
     ?-	   abba(X,Y), baba(X,Y), abba(Y,Y).