7 papers
Characteristic function of M. S. Livšic and triangular models of bounded linear operators
Vladimir K. Dubovoy, Bernd Kirstein, Conrad Mädler +1
This paper is dedicated to the introduction in a circle of ideas and methods, which are connected with the notion of characteristic function of a non-selfadjoint operator. We start…
Characteristic Function, Schur Parameters and Pseudocontinuation of Schur functions
Vladimir K. Dubovoy, Bernd Fritzsche, Bernd Kirstein +2
In [19] there is an approach to the investigation of the pseudocontinuability of Schur functions in terms of Schur parameters. In particular, there was obtained a criterion for the…
Characteristic Function, Schur Interpolation Problem and Darlington Synthesis
Sergey S. Boiko, Vladimir K. Dubovoy, Bernd Fritzsche +3
In this paper we would like to show the interrelation between the different mathematical theories concerning the Schur interpolation problem, contractions in Hilbert spaces, pseudo…
On the Matricial Truncated Moment Problem. II
Conrad Mädler, Konrad Schmüdgen
We continue the study of truncated matrix-valued moment problems begun in arXiv:2310.00957. Let . Suppose that is a measurable space an…
On the Truncated Matricial Moment Problem. I
Conrad Mädler, Konrad Schmüdgen
This paper is about the general truncated matrix-valued moment problem. Let denote the complex Hermitian -matrices, . Suppose that $(\ma…
A necessary condition for certain functions to preserve positive semi-definiteness on partitioned matrices
Lutz Klotz, Conrad Mädler
If is a symmetric complex-valued function on the -fold Cartesian product of the set of non-negative reals and is a positive semi-definite matrix with eigenva…