HW4 grading guide.  
Ex.2.11: this allows mutual recursion (see p. 64 of text).
It also allows use of a function that is defined elsewhere (e.g., in a
different file), by giving an extern directive.   5 points.  -1 if extern is
not mentioned, -3 points if mutual recursion is not mentioned.
Ex 2.13: macro processing binds identifiers before compile time (p.49); routine
parameters are bound at run time.  5 points.  
Ex 2.15: see p.66.  Also, note that this allows binding of an arbitrary subset
of parameters; in C, only a beginning subset of parameters may be bound.  5
points.  If students do not discuss the advantage w.r.t. C or C++ or Java, -1.
Ex. 2.16: If A is a real and I is an integer, EQUIVALENCE (A,I) allows the same
memory location to be addressed as both a real and an integer.  Since usually
reals and integers are represented differenty, the memory value in A (or I)
after A = A + 1  I = I + 1 is not well defined.  (Example from Pratt.)
5 points.

<p>
HW5 (PR1) 15 points.  10 for documenting that the student used simusem; 5 for
the proof of correctness.

<p>
PR2 grading guide.  10 points in total.  5 points per exercise.  

<p>
HW6 grading guide. 18.5 points in total.  
2.1.2 4.5 points in total, 0.5 point per exercise.
2.2.2 4 points in total, 0.5 points per exercise.
2.4.1 4 points in total, 0.5 points per exercise.
2.4.3 2 points in total, 0.5 points per exercise.
2.4.4 1 point: 0.5 points per part.
2.4.5 3 points in total, 0.5 points per part.

<p> 
PR3 grading guide.  24 points in total.
2.1.1 4 points in total, 0.5 points per exercise.
3.1.1 7 points in total, 1 point per exercise, except 2 points for (f).
3.1.2 8 points in total, 2 points per exercise.
3.2.1 5 points in total (a) 2 points, (d) 4 points.

<p>
PR4 grading guide.  20 points in total.
3.3.1 6 points in total, 1 point each.
3.3.2 2 points.
3.3.3 3 points.
3.3.8 3 points.
3.3.11 6 points, 2 points per paer.

<p>
PR5 grading guide.  4 points in total.
2 points off if the solution is not logarithmic in the exponent.

<p>
PR6 grading guide.  20 points in total.
4 points for the relations given by extension.
2 point for each of the 8 relations given intensionally (i.e., by rule).