Prolog queries can emulate SQL queries such as project, select, and join. The file xyz.pl contains the following tables:

student(S) asserts S is a student

instructor(Instructor)

taken(Student, Course, Result)

teaches(Instructor, Course)

prerequisite(Course, PreReqCourse)

Create rules for defining the following virtual tables:

academic(X) if X is a student or instructor

passed(X, Y) if X is a student who has passed course Y

studentOf(X, Y) if student X has taken a course from instructor Y

upperDivisionCSstudent(X) if X is a student who has passed all lower division CS courses

teachesPreReq(X) if X is an instructor who teaches a prerequisite course

canTake(X, Y) if X is a student who has passed all of the prerequisites for course Y

Careful, this last one is tricky. You might think this would work:

canTake(X, Y) :- prerequisite(Y, Z), taken(X, Z, pass).

But this is true if X has taken any prerequisite of course Y.

Try using Prolog's meta-predicate: foreach(predicate1, predicate2) if everything satisfying predicate1 also satisfies predicate2

xyz.pl:

student(smith). student(jones). student(nguyen). student(young). student(sherman). instructor(pearce). instructor(godel). instructor(escher). instructor(bach). taken(smith, cs46a, pass). taken(smith, cs46b, fail). taken(smith, cs146, pass). taken(jones, cs46a, pass). taken(jones, cs46b, pass). taken(jones, cs146, pass). taken(nguyen, cs46a, pass). taken(nguyen, cs46b, pass). taken(nguyen, cs151, pass). teaches(pearce, cs152). teaches(godel, cs151). teaches(escher, cs146). teaches(bach, cs46b). teaches(bach, cs46a). prerequisite(cs152, cs151). prerequisite(cs152, cs46b). prerequisite(cs151, cs46b). prerequisite(cs146, cs46b). prerequisite(cs46b, cs46a).