age(robespierre, 25). age(danton, 29). age(marat, 35). age(camus, 22). age(desmoulins, 19). eligible_for_event(Person) :- age(Person, Age), between(20, 30, Age). :- initialization(list_eligible_members). list_eligible_members :- eligible_for_event(Person), write('Citizen '), write(Person), write(' is eligible for the event.'), nl, fail.