Homework notes

I edited homework 4 to make it shorter and more focused so we can catch up with where we are in class. Please work on that. I think you already understand the issues that HW 3 examines, so let's just skip that if that's okay. Please post comments related to HW 4. Also, I think Ben's post will help a lot with one of the problems (problem 2?). The problems folowing that are related to what we worked on in class.