====== Course rules ======
{{tag>rules}}
===== Description =====
Course rules

**Source**:  The Art of Prolog
===== Download =====
Program source code: {{course_rules.pl}}
===== Listing =====
<code prolog>
	lecturer(Lecturer,Course) :-
		course(Course,Time,Lecturer,Location).

	duration(Course,Length) :-
		course(Course,time(Day,Start,Finish),Lecturer,Location),
		plus(Start,Length,Finish).

	teaches(Lecturer,Day) :-
		course(Course,time(Day,Start,Finish),Lecturer,Location).

	occupied(Room,Day,Time) :-
		course(Course,time(Day,Start,Finish),Lecturer,Location),
		Start =< Time, Time =< Finish.

%	Program 2.4: Course rules

</code>
===== Comments =====