4.5 and 4.6, due on October 7

1.Eisenstein's Criterion was a bit confusing at first, especially the seemingly arbitrary condition that p^2 does not divide a_0.  It makes sense after reading the proof, though.

2.I've seen most of the results in these sections before, so a lot of our reading was familiar.  I thought Lemma 4.21 was quite interesting, since it's not immediately obvious that you can't have the coefficients that are divisible by p be split up between g(x) and h(x).