Spectral Theory

The Asymptotic Behavior of the Solutions of the Wave Equation Concentrated near the Axis of a Two-Dimensional Waveguide in an Inhomogeneous Medium.- 1. A Waveguide in an Inhomogeneous Medium.- 2. The Construction of the Solutions of the Wave Equation Concentrated near the Waveguide Axis.- 3. The Asymptotic Behavior of the Eigenfunctions and Eigenvalues of the Boundary Problem for the Waveguide.- Literature Cited.- Perturbations of the Spectrum of the Schroedinger Operator with a Complex Periodic Potential.- 1. Preliminary Information.- 2. Investigations of the Perturbed Operator.- 3. Investigation of the Spectrum under the Condition $$\int{\left \text{q}\left( \text{x} \right) \right}{{\text{e}}^{\text{ }\!\!\delta\!\!\text{ }\left x \right}}dx$$ < ?.- 4. Proof That There Are No Eigenvalues on the Continuous Spectrum.- Literature Cited.- The Discrete Spectra of the Dirac and Pauli Operators.- 1. Auxiliary Information.- 2. The Discrete Spectrum of the Dirac Operator in the Case of Spherical Symmetry.- 3. The Discrete Spectrum of the Dirac Operator in the Three-Dimensional Case.- 4. The Discrete Spectrum of the Pauli Operator.- Literature Cited.- The Nonself-Adjoint Schroedinger Operator. III.- 1. Auxiliary Information.- 2. The Operator with Potential q(x) ? S?.- 3. The Operator with Potential q(x) ? Sn, n < ?.- Literature Cited.- The Singular Numbers of the Sum of Completely Continuous Operators.- Literature Cited.- Double-Integral Operators in the Ring R^.- Literature Cited.- Correction to The Inverse Problem in the Theory of Seismic Wave Propagation.