The question has four parts.  Probably shrink to 2 or 3.

This was from Spring00 PS6, so you can get the solutions from there.


Note that the injective subjctive material willNOT be covered
in lecture. So please make sure to mark that self-study.
Plesae check the readngs in Rosen, and you can also refer to
the lecture notes.  When the pigeonhole principle lecture
goes out, it will be in there.