
doi: 10.4171/emss/14
In this survey we establish bijective correspondences between the following classes of objects: (1) \beta_{-1} and \{ \beta_n \}_{n=0}^{\infty} , with \beta_n \in \mathbb C^{p \times p} for n=-1,0,\ldots , \beta_{-1} unitary, \| \beta_j \| < 1 for j \geq 0 and \sum_{j=0}^{\infty} \| \beta_j \| < \infty ; (2) A unitary matrix \beta_{-1} \in \mathbb C^{p \times p} and a spectral density \Delta belonging to the Wiener algebra \mathcal W^{p \times p} with \Delta(\zeta) \succ 0 for all \zeta on the unit circle \mathbb T ; (3) CMV matrices based on a unitary matrix \beta_{-1} \in \mathbb C^{p \times p} and a spectral density \Delta that meets the constraints in (2); (4) scattering matrices that belong to the Wiener algebra \mathcal W^{p \times p} ; (5) a class of solutions of an associated matricial Nehari problem. The bijective correspondence between summable sequences of contractions and positive spectral densities in the Wiener algebra \mathcal W^{p \times p} (i.e., between class (1) and class (2)) is known as Baxter's theorem and was established by Baxter when p=1 and Geronimo when p \geq 1 . The connections between CMV matrices, the solutions of a related Nehari problem and an inverse scattering problem seem to be new when p > 1 . There is partial overlap of the connection between the considered Nehari problem and a discrete analogue of an inverse scattering problem considered by Krein and Melik-Adamjan. de Branges spaces of vector-valued polynomials are used to ease a number of computations.
Baxter's theorem, Linear operators in reproducing-kernel Hilbert spaces (including de Branges, de Branges-Rovnyak, and other structured spaces), de Branges spaces, Jacobi (tridiagonal) operators (matrices) and generalizations, matrix orthogonal polynomials, Nehari problem, reproducing kernel Hilbert spaces, Schur parameters CMV matrices, Toeplitz operators, Hankel operators, Wiener-Hopf operators, Hilbert spaces with reproducing kernels (= (proper) functional Hilbert spaces, including de Branges-Rovnyak and other structured spaces), scattering matrices, Orthogonal functions and polynomials, general theory of nontrigonometric harmonic analysis, Linear operator methods in interpolation, moment and extension problems
Baxter's theorem, Linear operators in reproducing-kernel Hilbert spaces (including de Branges, de Branges-Rovnyak, and other structured spaces), de Branges spaces, Jacobi (tridiagonal) operators (matrices) and generalizations, matrix orthogonal polynomials, Nehari problem, reproducing kernel Hilbert spaces, Schur parameters CMV matrices, Toeplitz operators, Hankel operators, Wiener-Hopf operators, Hilbert spaces with reproducing kernels (= (proper) functional Hilbert spaces, including de Branges-Rovnyak and other structured spaces), scattering matrices, Orthogonal functions and polynomials, general theory of nontrigonometric harmonic analysis, Linear operator methods in interpolation, moment and extension problems
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