CS322, Fall 1997 - Solution to Midterm Exam -- Solution to Question 1, part (c)

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Solution to Question 1, part (c)

Clark's completion of the knowledge base:

passed_each([],St).
passed_each([C|R],St) <-
    passed(St,C) &
    passed_each(R,St).

passed_each(X,Y) <->
    (exist  St  X=[] & Y = St)  or 
    (exist  C exist  R exist  St  X=[C|R] & Y = St &
passed(St,C) & passed_each(R,St).)

You could also replace Y everywhere with St, and remove the exist St and Y=St.