This monograph presents the solution of the classical moment problem, the construction of Jacobi matrices and corresponding polynomials. The cases of strongly,trigonometric, complex and real two-dimensional moment problems are discussed, and the Jacobi-type matrices corresponding to the trigonometric moment problem are shown. The Berezansky theory of the expansion in generalized eigenvectors for corresponding set of commuting operators plays the key role in the proof of results.

The book is recommended for researchers in fields of functional analysis, operator theory, mathematical physics, and engineers who deal with problems of coupled pendulums.

- 1. Introduction. - 2. Some Aspects of the Spectral Theory of Unbounded Operators. - 3. Jacobi Matrices and the Classical Moment Problem. - 4. The Strong Moment Problem. - 5. Block Jacobi Type Matrices in the Complex Moment Problem. - 6. Unitary Block Jacobi Type Matrices and the Trigonometric Moment Problem. - 7. Block Jacobi Type Matrices and the Complex Moment Problem in the Exponential Form. - 8. Block Jacobi Type Matrices and the Two Dimensional Real Moment Problem. - 9. Applications of the Spectral Theory of Jacobi Matrices and Their Generalizations to the Integration of Nonlinear Equations.