Multidimensional inverse problem for the acoustic equation in the ray statement

This chapter deals with a multidimensional inverse dynamic problem for the acoustic equation. This problem is reduced to inverse kinematic, integral geometry problems, a Dirichlet problem for a quasilinear elliptic equation, and for some special case to standard tomography problems. The structure and some properties of the fundamental solution of the Cauchy problem for the acoustic equation are used for this reduction. The structure and properties are described in detail.