Problem 1:

Consider the following Scheme program:

(define x 10)
(define y 5)
(define (f x y)
  (+ x (local [(define (f x) (* x y)) (define y 2)] (f (* x x)))))

(f x y)

For each occurrence of x and y identify its value, if possible.

What is the result of this program?


Problem 2:

A peer-to-peer network (like GNUtella) consists of individual nodes
that are connected to the rest of the network through one or more
neighboring nodes. In a simplified model, each node has only one
neighbor and a list of files that it can serve. Every node has a
unique number representing its address.


(define-struct file (name contents))
(define-struct node (address files neighbor))


A P2P-Network is one of:
 - empty
 - (make-node number list-of-File P2P-Network)

A list-of-file is one of
 - empty 
 - (cons File list-of-file)

A File is a structure: (make-file symbol string)

Develop the function P2P-search. The function consumes the name of
file and a P2P-network and returns the address of the first node that
is discovered to have the file or false if the file does not exist
anywhere within the network.

Optional: A copyright enforcement group wants to collect the addresses
of all nodes on a P2P-Network that are hosting a particular
file. Develop the function P2P-search-all, which is like P2P-search
except that it returns the list of addresses of all nodes having a
copy of the file being searched for.


Problem 3:

Develop the function sort-auction-records-by-bid. The function
consumes a list of auction records and returns a list of auction
records sorted in decreasing order by bid amount.
    

An auction record is defined as follows:

    (define-struct auction (item id bid))

An auction record is a structure

    (make-auction String Number Number)