The college realizes that assigned advisers may not always be available to counsel students. Therefore, the college decides that when the assigned adviser is unavailable to counsel students, other faculty members can advise the student on degree requirements and/or register the student for classes. For example, when Matthew's faculty adviser is unavailable, he can get advice from Dr. Lucas on degree requirements and ask Dr. Chen to register him for a course. In addition, a student can ask multiple faculty members to register him/her for different classes. Therefore, for each degree-advising activity and course-registering activity, we want to keep track of the time (year_semester) of the activity, the faculty member who provides degree-advising, and the faculty member who registers the student for the course. The same faculty member can advise the same student on degree requirements at different year_semester times. The same faculty member can register the same student for classes at different year_semester times.