This lecture is part of my Berkeley math 115 course "Introduction to number theory"
For the other lectures in the course see • Introduction to number theory (Berkel...
We sketch how to show that Dirichlet L functions do not vanish at s=1, completing the proof of Dirichlet's theorem.
The textbook is "An introduction to the theory of numbers" by Niven, Zuckerman, and Montgomery (5th edition).