Introduction to vertex operator algebras II

This is the second part of the revised versions of the notes of three consecutive expository lectures given by Chongying Dong, Haisheng Li and Yi-Zhi Huang in the conference on Monster and vertex operator algebras at the Research Institute of Mathematical Sciences, Kyoto, September 4-9, 1994. In this part, we discuss the commutativity, the associativity, the Jacobi identity and the relations among them. We also discuss an analogue of endomorphism ring of a vector space in vertex operator algebra theory.