countable(lion).
countable(lecturer).
countable(nuig_student).

smarter(lion, lecturer).
chases(lion, lecturer).
chases(lion, nuig_student).
deadend(nuig_student).
caught(Y) :- chases(X,Y), smarter(X,Y).
caught(Y) :- chases(_,Y), deadend(Y).
chaser(X) :- chases(X,_).