Lecture notes 1: Cauchy-Davenport
inequality, Plunnecke's theorem, sum set estimates. Errata to Q2: |A|, |B| need to be assumed
to be at least 2. Errata to Q10(a):
"translates of B" should read "translates of B-B". Errata to Q11:
"and some subset A' such that |A'| >= (1-delta) |A| and" should read
"such that for every subset A' with |A'| >= (1-delta)|A|, we have". Thanks to Roman Sasyk for pointing out these
errata.