Is it rude to ask the lecturer whether there is any “effective prerequisite”? Situation: My university has an online course registration system. Students (including me) choose courses in the system and submit their requests at certain time.

Sometimes, the course information is not detailed enough. A lot of course information in the catalog contains no or unreasonable prerequisite. For example, no prerequisite is listed in the information of a MATH 4000-level (fourth-year) course about real analysis. Another example is that a CSCI 4000-level course about cloud computing has a very minimal prerequisite course (something like an introductory OS course).

I am not sure whether it would be rude to email the lecturer in advance, asking whether there is any prerequisite not stated in the online system. While I am feeling OK to ask the lecturer if none of the “effective prerequisite” is stated for a 4000-level course (as I believe there must be some), I feel a bit sorry in the second case because it appears that I don’t trust the department’s course director and I chose to, in some sense, challenge the lecturer.

I did send an email asking the prerequisite of the cloud computing course. Initially I expected the lecturer to require me to have some basic knowledge about, e.g. graph theory, database system etc. He replied to me that there is no other prerequisite, though. For some other reasons I decided not to take that course, but I think similar situations may appear in future.

Any help is appreciated.
I wouldn't phrase it in terms of "effective prerequisites".  But it's certainly fine to discuss with the professor whether you are adequately prepared.  You could visit their office hours, or send an email:


  Dear Professor So-And-So:
  
  I am interested in taking your course MATH 4321.  I see that no prerequisites are listed, but I was wondering what background knowledge is expected, and whether I'd be ready for this course.  I've taken related courses X, Y, Z and feel comfortable with the material from those courses, and have also had some experience with topic Q.  Does this seem sufficient?  If you can recommend specific topics to review, or additional reading, I would appreciate it.  Or, if there are other courses I should take first, that would also be helpful to know.


If you like you can attach a copy of your transcript.