1 ;; Exercise 3.40.  Give all possible values of x that can result from executing
2 
3 (define x 10)
4 
5 (parallel-execute (lambda () (set! x (* x x)))
6                   (lambda () (set! x (* x x x))))
7 
8 ;; 10^2, 10^3, 10^4, 10^5, 10^6
9 
10 ;; Which of these possibilities remain if we instead use serialized procedures:
11 
12 (define x 10)
13 
14 (define s (make-serializer))
15 
16 (parallel-execute (s (lambda () (set! x (* x x))))
17                   (s (lambda () (set! x (* x x x)))))
18 
19 ;; 10^6