Some error in the counting ¡­

Some error in the counting of problem sets have unfortunately occurred. Problem set 12 is already calculated last week. Tomorrow Problem 13.1 will be calculated/considered. Problem 13.2 has to be postponed because retarded fields has not yet been covered in the lectures. Instead of 13.2, the first problem from the final exam of 2011 will be calculated (This problem set will be put on the web).