1. Read Section 2.12.3 on page 147. 
    What is the difference between DefineOldGlobal and DefineNewGlobal?








    You are ready to start problem 44.


 2. Look at `mk-insertion-sort` in Section 2.9.2 (page 130).

    (a) Calling `(mk-insertion-sort >)` returns a function. What does
        the function do?



    (b) Given that the internal function `sort` (defined with `letrec`
        and `lambda`) takes only the list `xs` as argument, how does it
        know what order to sort in?




    You are ready to start problem Q.

 3. Look at the first paragraph of Exercise 21 on page 205. 
    Each bullet gives one possible rule for creating a formula.  For
    each bullet, write one example formula that is created using the
    rule for that bullet---four examples in total.

      * 

      * 

      * 

      * 


    You are ready to start problems F and T.



 4. Set aside an hour to study the conjunctive-normal-form solver in
    Section 2.10.1, which starts on page 133.  This will help you 
    a lot in solving Exercise 21.

    (a) Look at code chunk 137b on page 137. In English, describe how
        `(one-solution f)` produces the answer `((x #t) (y #f))`.
        Walk through each function call, what the input to the
        function is, how the input is processed, and what the output
        of the function call is. 
    



    (b) Look at code chunk 137d. As you did with 137b, describe how
        `(one-solution '((x) ((not x))))` produces the answer `no-solution`.  




    You are ready to start exercise 21.