Principal Functions of Non-Selfadjoint Difference Operator with Spectral Parameter in Boundary Conditions.

We investigate the principal functions corresponding to the eigenvalues and the spectral singularities of the boundary value problem (BVP) an-1yn-1 + bnyn + anyn+1 = λyn, n ∈ ℕ and (γ0 + γ1λ)y1 + (β0 + β1λ)y0 = 0, where (an) and (bn) are complex sequences, λ is an eigenparameter, and γi, βi ∈ ℂ for i = 0, 1. [ABSTRACT FROM AUTHOR]