Representation theory: Abelian groups

This lecture discusses the complex representations of finite abelian groups. We show that any group is iomorphic to its dual (the group of 1-dimensional representations, and isomorphic to its double dual in a canonical way (Pontryagin duality). We check the orthogonality relations for the character table. Finally we give a few examples to show the extra complications one gets if we drop the assumption that the group is finite or the field is the complex numbers.