Since May 2019 I am affiliated with the Department of Applied Mathematics. Before I was a post-doc at the University of Hamburg and the University of Wuppertal, where I also held a temporary professor position (`Vertretungsprofessor') in Fall 2018/19. My mathematical origins (undergraduate studies) are at the TU Wien.

My research interests broadly center around (functional) analysis and particularly operator theory with applications in the analysis and control of pde's.

In more detail, some research foci have been semigroup theory, functional calculus, input-to-state stability of infinite-dimensional systems and funnel control.

Besides, I like optimising constants and Crouzeix's conjecture.

Expertise

  • Mathematics

    • Admissibility
    • Semigroup
    • Operators
    • Control System
    • Dimensional System
    • Parabolic
    • Functional Calculus
  • Computer Science

    • Control

Organisations

See here:  here

Publications

2025

On BIBO stability of infinite-dimensional systems (2025)[Thesis › PhD Thesis - Research UT, graduation UT]. Wierzba, A. A.The algebraic numerical range as a spectral set in Banach algebras (2025)Canadian journal of mathematics. Blazhko, H., Homza, D., Schwenninger, F. L., de Vries, J. & Wojtylak, M.https://doi.org/10.4153/S0008414X25000124The algebraic numerical range as a spectral set in Banach algebras (2025)Canadian journal of mathematics (E-pub ahead of print/First online). Blazhko, H., Homza, D., Schwenninger, F. L., De Vries, J. & Wojtylak, M.https://doi.org/10.4153/S0008414X25000124

2024

A dual notion to BIBO stability (2024)Journal of mathematical analysis and applications, 545(2). Article 129156 (E-pub ahead of print/First online). Schwenninger, F. & Wierzba, A. A.https://doi.org/10.1016/j.jmaa.2024.129156A sharp bound for the functional calculus of ρ-contractions (2024)[Working paper › Preprint]. ArXiv.org. de Vries, J. & Schwenninger, F. L.https://doi.org/10.48550/arXiv.2412.02326

Research profiles

I'm teaching several Bachelor and Master courses within the Applied Mathematics programme -- typically in the areas of analysis and control as well some service teaching. This includes courses within the Dutch-wide MasterMath programme. Furthermore, I coordinate the Math Track of the University's Honours Bachelor programme. Currently, I'm also involved in teaching within the Dutch Institute for Systems and Control.

Courses academic year 2024/2025

Courses in the current academic year are added at the moment they are finalised in the Osiris system. Therefore it is possible that the list is not yet complete for the whole academic year.

Courses academic year 2023/2024

Currently running projects:

  • Predictive Avator Control and Feedback (together with Robotics and Computer Science): PhD student: Alexander Wierzba
  • Optimal Constant as Analytic Benchmarks (OCAB), NWO-funded (Open Competite), PhD student: Jens de Vries
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