Help with SICP

http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-10.html#%_sec_1.1.6
Exercise 1.3 is a bitch. I think I'm close to a solution, then I see a fundamental flaw, and have to rewrite it. My notebook paper hurts.

>>2
Actually, there's 13 cases:
x > y > z
x > z > y
y > x > z
y > z > x
z > x > y
z > y > x
(x = y) > z
(x = y) < z
(x = z) > y
(x = z) < y
(y = z) > x
(y = z) < x
x = y = z