The focussing problem and spectral function asymptotics of Laplace– Beltrami operator. II

The subject of the paper is the construction of formal high frequency solution of the source problem in the neighbourhood of a reflecting boundary. The boundary is geodesically concave. It gives the possibility to use diffraction methods by V. A. Fock. and J. B. Keller. The formal solution of the source problem is applied to obtain the asymptotics of spectral function of Laplace–Beltrami operator.