Nonself-Adjoint Second-Order Difference Operators in Limit-Circle Cases.

We consider the maximal dissipative second-order difference (or discrete Sturm-Liouville) operators acting in the Hilbert space lw² (Z) (Z:= {0, ±1, ±2, . . .}), that is, the extensions of a minimal symmetric operator with defect index (2, 2) (in the Weyl-Hamburger limit-circle cases at ±8). We investigate two classes of maximal dissipative operators with separated boundary conditions, called "dissipative at -8" and "dissipative at 8." In each case, we construct a self-adjoint dilation of the maximal dissipative operator and its incoming and outgoing spectral representations, which make it possible to determine the scattering matrix of the dilation. We also establish a functional model of the maximal dissipative operator and determine its characteristic function through the Titchmarsh-Weyl function of the self-adjoint operator. We prove the completeness of the system of eigenvectors and associated vectors of the maximal dissipative operators. [ABSTRACT FROM AUTHOR]