30 citations · 91 across the 25 of their papers we have counts for
6 papers · 1 filter
Stability of square root domains associated with elliptic systems of PDEs on nonsmooth domains
Fritz Gesztesy, Steve Hofmann, Roger Nichols
We discuss stability of square root domains for uniformly elliptic partial differential operators in , with mixed boundary conditions on…
On a problem in eigenvalue perturbation theory
Fritz Gesztesy, Sergey N. Naboko, Roger Nichols
We consider additive perturbations of the type , , where and are self-adjoint operators in a separable Hilbert space and is boun…
On Factorizations of Analytic Operator-Valued Functions and Eigenvalue Multiplicity Questions
Fritz Gesztesy, Helge Holden, Roger Nichols
We study several natural multiplicity questions that arise in the context of the Birman-Schwinger principle applied to non-self-adjoint operators. In particular, we re-prove (and e…
A Jost-Pais-type reduction of (modified) Fredholm determinants for semi-separable operators in infinite dimensions
Fritz Gesztesy, Roger Nichols
We study the analog of semi-separable integral kernels in of the type $$ K(x,x')=\begin{cases} F_1(x)G_1(x'), & a<x'< x< b, \\ F_2(x)G_2(x'), & a<x<x'<b, \end{cases}…
Inverse Spectral Problems for Schrödinger-Type Operators with Distributional Matrix-Valued Potentials
Jonathan Eckhardt, Fritz Gesztesy, Roger Nichols +2
The principal purpose of this note is to provide a reconstruction procedure for distributional matrix-valued potential coefficients of Schrödinger-type operators on a half-line fro…
Principal Solutions Revisited
Stephen Clark, Fritz Gesztesy, Roger Nichols
The main objective of this paper is to identify principal solutions associated with Sturm-Liouville operators on arbitrary open intervals , as introduce…