Solution of a nonlocal problem of the first kind for a hyperbolic equation

The spectral method is applied to establish solvability in the class of finite-energy generalized solutions of the mixed problem for a hyperbolic equation with a nonlocal boundary condition of the first kind. The solution is representable as a biorthogonal series in the root functions of the corresponding spectral problem. __________ Translated from Nelineinaya Dinamika i Upravlenie, No. 4, pp. 167–178, 2004.