Institut für Angewandte Mathematik
Seminar Operator Theory

This seminar is devoted to current research talks in the field of operator theory and its applications. It regularly takes place on Thursday, 12:15, in the seminar room AE02, Steyrergasse 30, ground floor, but time and place may change. The seminar is organized by Univ.-Prof. Dr. Jussi Behrndt, Assoc.Prof. Dr. Petr Siegl, and Dr. Markus Holzmann.

2025
20.11.2025Eduard Stefanescu (TU Graz)
Random Schrödinger operators on compact manifolds II
12:15, SR AE02, Steyrergasse 30, ground floor
13.11.2025Eduard Stefanescu (TU Graz)
Random Schrödinger operators on compact manifolds I
12:15, SR AE02, Steyrergasse 30, ground floor
6.11.2025Peter Schlosser (TU Graz)
The Neumann trace for unbounded Lipschitz domains
12:15, SR AE02, Steyrergasse 30, ground floor
30.10.2025Patrick Ebnicher (TU Graz)
Sectorial and accretive Schrödinger operators on unbounded domains II
12:15, SR AE02, Steyrergasse 30, ground floor
23.10.2025Patrick Ebnicher (TU Graz)
Sectorial and accretive Schrödinger operators on unbounded domains I
12:15, SR AE02, Steyrergasse 30, ground floor
16.10.2025Jan Havel (TU Graz)
Laplacian with delta-potential supported on a point in 3D
12:15, SR AE02, Steyrergasse 30, ground floor
9.10.2025Nicolas Weber (TU Graz)
Absence of zero as an eigenvalue of non-self-adjoint Schrödinger operators II
12:15, SR AE02, Steyrergasse 30, ground floor
2.10.2025Nicolas Weber (TU Graz)
Absence of zero as an eigenvalue of non-self-adjoint Schrödinger operators I
12:15, SR AE02, Steyrergasse 30, ground floor
18.8.2025Sandeep Kumar Soni (TU Graz)
Spectral analysis of Friedrichs systems (i), abstract
12:15, SR AE02, Steyrergasse 30, ground floor
7.8.2025Kiyan Naderi (TU Graz)
Transmission Problems on Infinite Metric Trees Coupled to Euclidean Domains
12:15, SR AE02, Steyrergasse 30, ground floor
2.7.2025Jan Havel (CTU Prague, Czech Republic)
Spectral theory of black holes
13:00, SR AE02, Steyrergasse 30, ground floor
12.6.2025Markus Holzmann (TU Graz)
Dirac operators with distributional potentials supported on curves in R^2 and surfaces in R^3
13:30, SR AE02, Steyrergasse 30, ground floor
23.5.2025Markus Holzmann (TU Graz)
Extension theory for restricted fractional Laplacians on bounded intervals
17:00, SR AE02, Steyrergasse 30, ground floor
23.5.2025Nicolas Weber (TU Graz)
Eigenvalues of operator functions: A commutativity result with an application to 1D Dirac operators
16:30, SR AE02, Steyrergasse 30, ground floor
23.5.2025Henrik Winkler (TU Ilmenau, Germany)
Decompositions of linear relations and DAEs
16:00, SR AE02, Steyrergasse 30, ground floor
23.5.2025Rudi Wietsma (Vaasa, Finland)
Factorizations of generalized Nevanlinna functions
15:00, SR AE02, Steyrergasse 30, ground floor
23.5.2025Michael Kaltenbäck (TU Wien)
A review on results on Friedrichs extension by Henk and Earl Coddington
14:30, SR AE02, Steyrergasse 30, ground floor
23.5.2025Seppo Hassi (Vaasa, Finland)
On the product of two nonnegative operators and beyond
14:00, SR AE02, Steyrergasse 30, ground floor
10.4.2025Francesco Mantovani (Politecnico di Milano, Italy)
The S-functional calculus for the adjoint operator in the quaternionic setting, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
3.4.2025Markus Holzmann
Symmetries for Dirac operators on graphs
12:15, SR AE02, Steyrergasse 30, ground floor
27.3.2025Patrick Ebnicher
Riesz Projection and Spectral Analysis of Compact Operators
12.15 Uhr, Seminarraum AE02, Steyrergasse 30, Erdgeschoss
13.3.2025Perry Kleinhenz (Illinois State University, USA)
Energy decay rates for the damped wave equation on the torus via non-polynomial derivative bound conditions, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
27.2.2025Lawrence Frolov (Rutgers University, USA)
Irreversible hard detection of non-relativistic quantum particles, abstract
15:00, SR AE02, Steyrergasse 30, ground floor
27.2.2025Joaquim Duran (Centre de Recerca Matematica and Universitat Politecnica de Catalunya, Barcelona, Spain)
Convergence of generalized MIT bag operators close to zigzag boundary conditions, abstract
14:15, SR AE02, Steyrergasse 30, ground floor
11.2.2025Christian Stelzer
Approximation of Dirac Operators with delta-shell Potentials in the Norm Resolvent Sense
11:00, SR AE02, Steyrergasse 30, ground floor
30.1.2025Badreddine Benhellal (Universität Oldenburg)
On Schrödinger operators with oblique transmission conditions on non-smooth curves, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
19.12.2024Petr Siegl
Local form subordination without a power decay and a criterion of Riesz basesness, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
16.1.2025Jussi Behrndt
Generalized boundary triples for adjoint pairs
12:15, SR AE02, Steyrergasse 30, ground floor
2024
19.12.2024Peter Schlosser
Oscillatory integrals, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
12.12.2024Nicolas Weber
Eigenvalues of operator functions: A commutativity result with an application to 1D Dirac operators, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
5.12.2024Lukas Heriban (CTU Prague)
Non-relativistic limit of generalized MIT bag models on a straight line, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
14.11.2024Sandeep Kumar Soni (University of Zagreb)
Friedrichs system: a unified approach for studying various types of PDEs, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
13.11.2024Johannes Ladreiter
Schrödinger operators with oblique transmission conditions and complex interaction strenghts
13:00, SR AE02, Steyrergasse 30, ground floor
7.11.2024Markus Holzmann
Boundary triples for the fractional Laplacian on an interval
12:15, SR AE02, Steyrergasse 30, ground floor
24.10.2024Andrea Mantile (Laboratoire de Mathematiques de Reims)
Scattering theory with both regular and singular perturbations and applications, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
17.10.2024Iveta Semoradova (CTU Prague & Cardiff University)
PT-symmetric oscillators with one-centre point interactions, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
17.9.2024Matej Tusek (CTU Prague)
On Iwatsuka-like models, abstract
11:00, SR AE02, Steyrergasse 30, ground floor
26.6.2024Eduard Stefanescu (TU Graz)
Global-in-time existence, uniqueness and stability of solutions to a model of the Antarctic Circumpolar Current, abstract
13:30, SR AE02, Steyrergasse 30, ground floor
20.6.2024Jussi Behrndt
Spectral instability of the Neumann and Krein-von Neumann extension
12:15, SR AE02, Steyrergasse 30, ground floor
29.5.2024Rafael Benedikt Andrist (University of Ljubljana)
Symplectic holomorphic automorphisms of Calogero-Moser spaces, abstract
12:00, SR AE02, Steyrergasse 30, ground floor
16.5.2024Christian Stelzer (TU Graz)
Approximation of Dirac operators with delta-potentials: Explicit conditions, counterexamples and semi-local potentials
12:15, HS AE01, Steyrergasse 30, ground floor
2.5.2024Bao Quoc Tang (Karl Franzens Universität)
Close-to-equilibrium regularity for reaction-diffusion systems, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
25.4.2024Markus Holzmann
On the non-essential self-adjointness of Robin Laplacians restricted to subsets of H^(3/2+s)
13:00, SR AE02, Steyrergasse 30, ground floor
25.4.2024Christian Emmel (Stockholm University, Sweden)
Operator models for meromorphic functions of bounded type, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
18.4.2024Jean-Claude Cuenin (Loughborough University/TU Graz)
Spectral cluster bounds for orthonormal functions, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
11.4.2024Georg Stenzel
Spectral analysis of generalised Robin and Neumann Laplacians in R^2
12:15, SR AE02, Steyrergasse 30, ground floor
21.3.2024Nicolas Weber
Weakly coupled bound states for one-dimensional Schrödinger operators with complex potentials
12:15, SR AE02, Steyrergasse 30, ground floor
14.3.2024Sahiba Arora (University of Twente, Netherlands)
An anti-maximum principle for the Dirichlet-to-Neumann operator, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
7.3.2024Selim Sukhtaiev (Auburn University, USA)
The Maslov index in spectral theory: an overview, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
7.3.2024Julien Royer (Universite Toulouse, France)
Local energy decay and low frequency asymptotics for the Schrödinger equation, abstract
13:00, SR AE02, Steyrergasse 30, ground floor
25.1.2024Delio Mugnolo (Fernuniversität Hagen)
Pointwise eigenvector estimates by landscape functions, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
18.1.2024Nicolas Weber
Bound states of weakly coupled Schrödinger operators with complex-valued regular potentials in two dimensions
12:15, SR AE02, Steyrergasse 30, ground floor
2023
21.12.2023Petr Siegl
Energy decay for the wave equation with a damping coefficient unbounded at infinity
10:00, SR AE02, Steyrergasse 30, ground floor
21.12.2023Johannes Ladreiter
Schrödinger operators with oblique transmission conditions and complex interaction strenghts in R^2
10:45, SR AE02, Steyrergasse 30, ground floor
21.12.2023Nicolas Weber
Eigenvalues of the Schrödinger operator in 2D with a constant complex-valued singular potential supported on the unit circle
13:30, SR AE02, Steyrergasse 30, ground floor
21.12.2023Peter Schlosser
Quaternionic Hilbert spaces and the S-spectrum
14:15, SR AE02, Steyrergasse 30, ground floor
14.12.2023Sabine Bögli (Durham University, UK)
Numerical ranges and multiplier tricks, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
7.12.2023Jussi Behrndt
Spectral instability of the Krein-von Neumann extension, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
22.11.2023Carsten Trunk (TU Ilmenau)
Essential spectra of Sturm-Liouville operators, abstract
16:00, SR AE06, Steyrergasse 30, ground floor
16.11.2023Antonio Arnal (TU Graz)
Resolvent estimates for one-dimensional Dirac operators with complex potentials, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
9.11.2023Vladimir Lotoreichik (Czech Academy of Sciences, Prague)
Spectral asymptotics of the Dirac operator on a thin shell, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
19.10.2023Nicolas Weber (TU Graz)
Schrödinger operators with complex delta-interactions on the (n-1)-dimensional hyperplane
12:15, SR AE02, Steyrergasse 30, ground floor
12.10.2023Markus Holzmann (TU Graz)
Nonrelativistic limit of generalized MIT bag models
12:15, SR AE02, Steyrergasse 30, ground floor
5.10.2023Delio Mugnolo (Fernuniversität Hagen)
Spectral Estimates for Laplace operators, Geometry of Graphs, and Expanders, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
28.9.2023Nathanael Skrepek (TU Freiberg)
Boundary triples with quasi Gelfand triples, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
2.8.2023Bernhard Aigner
Über geometrische Eigenschaften von Banachräumen
12:30, SR AE06, Steyrergasse 30, ground floor
22.6.2023Georg Stenzel (TU Graz)
Spectral analysis of Schrödinger operators with oblique transmission conditions in R^2
12:15, SR AE02, Steyrergasse 30, ground floor
15.6.2023Matej Tusek (CTU Prague)
Echoes of the Klein paradox in approximations of the relativistic point interactions, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
15.6.2023Lukas Heriban (CTU Prague)
Non-local relativistic delta shell interactions, abstract
13:00, SR AE02, Steyrergasse 30, ground floor
25.5.2023Markus Holzmann (TU Graz)
Approximation of magnetic Schrödinger operators with electric delta-potentials supported on networks
12:15, SR AE02, Steyrergasse 30, ground floor
11.5.2023Petr Siegl (TU Graz)
Generalized Airy Operators, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
4.5.2023Fritz Gesztesy (Baylor University, Waco, TX, USA)
Some recent developments in Hardy-type inequalities, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
27.4.2023Henk de Snoo (University of Groningen, Netherlands)
Boundary triplets and Weyl functions for the Bessel operator
12:15, SR AE02, Steyrergasse 30, ground floor
23.3.2023Marco Vogel (Universität Oldenburg)
Spectral properties of Robin-Laplacians on sharp infinite cones, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
16.3.2023Nicolas Weber (TU Graz)
Spectral asymptotics of Landau Hamiltonians under delta perturbations (with Toeplitz operators) in R^2
12:15, SR AE02, Steyrergasse 30, ground floor
9.3.2023Iveta Semoradova (TU Graz)
Asymptotic behaviour of eigenfunctions of Schrödinger operators
12:15, SR AE02, Steyrergasse 30, ground floor
26.1.2023Romana Kvasničková (CTU Prague / TU Graz)
Weakly coupled eigenvalues
12:15, SR AE02, Steyrergasse 30, ground floor
19.1.2023Dale Frymark (TU Graz)
Non-relativistic limits of Dirac Operators in Confinement
12:15, SR AE02, Steyrergasse 30, ground floor
12.1.2023Georg Stenzel (TU Graz)
Schrödinger operators with generalized oblique transmission conditions
12:15, SR AE02, Steyrergasse 30, ground floor
2022
15.12.2022Zhu Li
On essential numerical ranges and essential spectra of linear Hamiltonian systems with one singular endpoint
12:15, SR AE02, Steyrergasse 30, ground floor
1.12.2022Christian Stelzer
Approximation of Dirac operators with delta-potentials
12:15, SR AE02, Steyrergasse 30, ground floor
17.11.2022Borbala Gerhat (CTU Prague)
An improved discrete Rellich inequality on the half-line, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
3.11.2022Sabine Bögli (Durham University, GB)
Constructing Schrödinger operators with prescribed eigenvalues, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
3.11.2022Fritz Gesztesy (Baylor Universit, USA)
Sturm–Liouville M-Functions in Terms of Green’s Functions
13:00, SR AE02, Steyrergasse 30, ground floor
20.10.2022Georg Stenzel (TU Graz)
Schrödinger operators with oblique transmission conditions in R^2
12:15, SR AE02, Steyrergasse 30, ground floor
13.10.2022Romana Kvasničková (CTU Prague / TU Graz)
Absence of embedded boundstates in semi-Dirac semi-metals, abstract
12:15, SR AE02, Steyrergasse 30, ground floor
6.10.2022Seppo Hassi (University of Vaasa, Finland)
Representation theorems for general semibounded forms
12:15, SR AE02, Steyrergasse 30, ground floor
6.10.2022Henk de Snoo (University of Groningen, Netherlands)
Friedrichs and Krein type extensions
13:00, SR AE02, Steyrergasse 30, ground floor