Spectral Methods of Automorphic Forms

Automorphic forms are one of the central topics of analytic number theory. In fact, they sit at the confluence of analysis, algebra, geometry, and number theory. This book treats the spectral theory of automorphic forms as the study of the space $L^2 (H\Gamma)$ and $\Gamma$ is a discrete subgroup of volume-preserving transformations of $H$.