 Homework is due every Tuesday at the beginning of class.
 Challenge problems will be collected on the last lecture day.
 Please staple your homework.
 Collaborations are welcome however you must turn in your
own copy and list on it the names of your collaborators.
 Write legibly and indicate clearly, where a new problem starts.
 Try to keep the problems in order.
 Use words to explain your work, if necessary. Show your work.
 If unable to finish a problem, indicate where you are
stuck. This will help us to give partial credit.
 Please infom about typos, misprints. We state here corrections
to the in class distributed texts as well as to the posted solutions.
Each hint gives you a bonus point. The texts posted here are corrected.
 (+Sol) means solutions have been posted.
