Here is the policy I use for issues related to admitting students into
424, which seems almost routinely oversubscribed:

* I do not waive the prerequisite.

* I typically do not overrule decisions made by the CS Undergraduate office.

* If you need special permission to register or join the waitlist, you
will need to wait until after the first class meeting (which you
should attend).  Do NOT send me requests for permission early.

* I prioritize students (for the purposes of admisssion into 424) as follows:
   * CS seniors
   * CS undergrads
   * CS grad students
   * other seniors
   * other undergrads
   * other grad students
Clarifications: (1) A student in category x who is on the waiting list
gets admitted only if everyone else on the waiting list who has a
higher priority has been admitted. (2) Typically, the lower priority
categories are never reached.  So if you are, for example, a non-CS
grad student, your chances of getting in are slim.

* I may make exceptions for truly outstanding students.  If you
believe you fall in this category, include supporting evidence in your
message to me.  (Note: I plan to make at *most* one such exception a
year, so set your expectations accordingly.)