2.61.scm~

#lang scheme/base
(define (element-of-set? x set)
  (cond ((null? set) #f)
        ((= x (car set)) #t)
        ((< x (car set)) #f)
        (else (element-of-set? x (cdr set)))
        )
  )

(define (adjoin-set x set)
  (cond ((null? set) (list x))
        ((< x (car set)) (cons x set))
        (else (cons (car set) (adjoin-set x (cdr set))))
        )
  )