227 citations · 812 across the 43 of their papers we have counts for
7 papers · 1 filter
Spectral asymptotics for canonical systems
Jonathan Eckhardt, Aleksey Kostenko, Gerald Teschl
Based on continuity properties of the de Branges correspondence, we develop a new approach to study the high-energy behavior of Weyl-Titchmarsh and spectral functions of …
On Spectral Deformations and Singular Weyl Functions for One-Dimensional Dirac Operators
Alexander Beigl, Jonathan Eckhardt, Aleksey Kostenko +1
We investigate the connection between singular Weyl-Titchmarsh-Kodaira theory and the double commutation method for one-dimensional Dirac operators. In particular, we compute the s…
The inverse spectral problem for indefinite strings
Jonathan Eckhardt, Aleksey Kostenko
Motivated by the study of certain nonlinear wave equations (in particular, the Camassa-Holm equation), we introduce a new class of generalized indefinite strings associated with di…
Quadratic operator pencils associated with the conservative Camassa-Holm flow
Jonathan Eckhardt, Aleksey Kostenko
We discuss direct and inverse spectral theory for a Sturm-Liouville type problem with a quadratic dependence on the eigenvalue parameter, which arises as the isospectral problem fo…
An isospectral problem for global conservative multi-peakon solutions of the Camassa-Holm equation
Jonathan Eckhardt, Aleksey Kostenko
We introduce a generalized isospectral problem for global conservative multi-peakon solutions of the Camassa-Holm equation. Utilizing the solution of the indefinite moment problem…
A note on J-positive block operator matrices
Aleksey Kostenko
We study basic spectral properties of J-self-adjoint block operator matrices. Using the linear resolvent growth condition, we obtain simple necessary conditions for the…