attends(P,D) <- proctors_exam(P,C) & exam(C,D).
proctors_exam(P,C) <- instructor(P,C).
proctors_exam(P,C) <- teaching_assistant(P,C).
exam(cs322,oct22).
exam(cs322,dec24).
instructor(david,cs322).
teaching_assistant(rita,cs322).
teaching_assistant(leslie,cs322).