Torsion points on modular curves and Galois theory
arXiv:math/0305281
Abstract
We outline the proof of a theorem of M. Baker and A. Tamagawa that gives a complete description of the torsion points on a modular curve embedded in its Jacobian using the notion of an `almost rational torsion point.'
Based upon lectures by K.A. Ribet at the University of Arizona in May 1999