Theorems of factorising matrix functions and the operator identity method play an essential role in this book in constructing the spectral theory (direct and inverse problems) of canonical differential systems. Includes many varied applications of the general theory.

Inhalt

1 Factorization of Operator-valued Transfer Functions.- 1.1 Realization of operator-valued functions.- 1.2 A factorization method.- 1.3 Factorization of rational operator-valued functions.- 2 Operator Identities and S-Nodes.- 2.1 Elementary properties of S-nodes.- 2.2 Symmetric S-nodes.- 2.3 Inherited properties of factors.- 3 Continual Factorization.- 3.1 The main continual factorization theorem.- 3.2 Bounded operator-valued functions.- 4 Spectral Problems on the Half-line.- 4.1 Basic notions of spectral theory.- 4.2 Direct and inverse spectral problems.- 4.3 LivSic-Brodski? nodes and the spectral theory of canonical systems.- 5 Spectral Problems on the Line.- 5.1 Spectral data of a canonical system.- 5.2 Spectral problems and S-nodes.- 5.3 The inverse spectral problem.- 6 Weyl-Titchmarsh Functions of Periodic Canonical Systems.- 6.1 Multipliers and their behavior.- 6.2 Weyl-Titchmarsh functions.- 6.3 Singular points of the Weyl-Titchmarsh matrix function.- 7 Division of Canonical Systems into Subclasses.- 7.1 An effective solution of the inverse problem.- 7.2 Two principles of dividing a class of canonical systems into subclasses.- 8 Uniqueness Theorems.- 8.1 Monodromy matrix and uniqueness theorems.- 8.2 Spectral data and uniqueness theorems.- 9 Weyl Discs and Points.- 9.1 Basic notions.- 9.2 Symmetric operators and deficiency indices.- 9.3 Weyl-Titchmarsh matrix functions on the line.- 9.4 Weyl-Titchmarsh matrix function of a system with shifted argument.- 10 A Class of Canonical Systems.- 10.1 Asymptotic formulas.- 10.2 Spectral analysis.- 10.3 Transformed canonical systems.- 10.4 Dirac-type systems.- 10.5 An inverse problem.- 10.6 On the limit Titchmarsh-Weyl function.- 11 Classical Spectral Problems.- 11.1 Generalized string equation (direct spectral problem).- 11.2 Matrix Sturm-Liouville equation (direct spectral problem).- 11.3 Inverse spectral problem.- 12 Nonlinear Integrable Equations and the Method of the Inverse Spectral Problem.- 12.1 Evolution of the spectral data.- 12.2 Some classical nonlinear equations.- 12.3 On the unique solvability of the mixed problem.- 12.4 A hierarchy of nonlinear equations and asymptotic behavior of Weyl-Titchmarsh functions.- Comments.- References.