Find an element of list in lists in list

Question

I need a procedure which takes a list and checks if an element is part of that list even when the list contains lists. So far, I\'ve written this:

(define (elem         


        

Answer 1

You just need another clause to check if the car is a list. Add this to your cond (after the eq? clause):

((list? (car set))
 (or (element-of-set? element (car set))
     (element-of-set? element (cdr set))))

This recurses on any sublists.