Each group of people grading a problem came up with the grading guide for the problem.
This is just an attempt to capture what were the rules of thumb.

1.	4 points for the base case 
		-2pt for not starting at k=0

	4 points for the correct induction hypothesis
		-2pt for not doing strong induction or assuming 2 adjacent k's
		-1pt if I.H. says assume fot k>=2 then prove for k+1
	6 points for a correct inductive step
		-1pt for not saying why you can make assumptions about the height of the second subtree
		-3pt for saying saying that both subtrees have height k
		-1pt for not labeling where the I.H. is used in the proof
	2 points for the conclusion

2. Every correct output is worth two points

3.a)    4 points for using instanceof
	2 points for making the counters static
	2 points for making it work

  b)    2 points for changing the left and right subtrees to private
	1 point for saying that the should use getters and setters
	4 points for saying that they should checking that both left and right are (non) null in the constructor.
	1 point for saying that they should use one setter that takes two arguments
	
 
4. Every question is worth one point

5. 4 points if B is the root of the tree. 6 points for every correct subtree (?)

6. 3 points for checking if c1==null && c2==null 
   5 points for checking if either c1==null or c2==null
   5 points for checking which datum is greater
   7 points for calling lex recursively
   Non recursive solutions got 5 points max