Аңдатпа
In this paper we consider a non-local problem for a Laplace operator in a two-dimensional bounded symmetric domain with center at the origin. Investigated problem is an analogue of the classical periodic boundary value problems in the case of non-rectangular region. We prove self-adjointness of the problem and show a method of constructing eigenfunctions. We obtain an analogue of the Rayleigh type inequality and some spectral inequalities for the first eigenvalue of the nonlocal problem.