2 ;; sets as ordered lists.
4 (define (element-of-set? x set)
8 (else (element-of-set? x (cdr set)))))
10 (define (intersection-set set1 set2)
11 (cond ((or (null? set1)
15 (cons (car set1) (intersection-set (cdr set1)
17 ((< (car set1) (car set2)) (intersection-set (cdr set1) set2))
18 ((> (car set1) (car set2)) (intersection-set set1 (cdr set2)))))