/* file: /230/pl/appendl.pl */
/* append with difference lists */

adl(d(X,Y), d(Y,Z), d(X,Z)).

q1(Z) :- adl(d([1, 2, 3| X], X), d([4, 5 |Y], Y), Z).
q2(X) :- adl(d([1, 2, 3| X], X), d([4, 5 |Y], Y), Z).
q3(Y) :- adl(d([1, 2, 3| X], X), d([4, 5 |Y], Y), Z).