Week 5-6 : Introduction to Calculus of Residues
Cauchy integral theorem:
It is also known as the Cauchy–Goursat theorem in complex analysis, named after Augustin-Louis Cauchy (and Édouard Goursat), is an important statement about line integrals for holomorphic functions in the complex plane. Essentially, it says that if two different paths connect the same two points, and a function is holomorphic everywhere in between the two paths, then the two path integrals of the function will be the same.
Laurent Expantion and Singularities are also discussed in these lectures.