Investigation of the Dimension of the Spectral Projection of a Self-Adjoint Second-Order Quasidifferential Operator

Let lambda(1) and lambda(2) be real, lambda(1 )<lambda(2) functions be solutions to the second order quasidif lambda 1 lambda 2 lambda 1 < lambda 2 , psi - ( lambda i , t ) ferential equations , satisfying a homogeneous boundary condition at point L = i Pi = 1,2, psi - lambda psi - 0 a . We express the number of eigenvalues of operator L belonging to the interval( lambda( 1) , lambda (2) ) (or the dimension of its spectral projection relative to the interval ) in terms of the number of zeros of the Vron( lambda( 1) , lambda (2 )) skian composed for the functions and psi- (lambda(1) , t ) psi - ( lambda (2) , t ).