104 citations · 288 across the 40 of their papers we have counts for
44 papers
ISS and integral ISS coincide for linear systems with bounded inputs
Sahiba Arora, Philip Preußler, Felix Schwenninger
We show that input-to-state stability (ISS) and integral input-to-state stability (integral ISS) with respect to the space of essentially bounded functions are equivalent propertie…
A solution to Crouzeix's conjecture
Emiel Lorist, Felix Schwenninger
We provide a proof of Crouzeix's conjecture, which combines the tools developed previously for weaker estimates with a simple perturbation lemma for -dilations. Applying the lem…
A sharp bound for the functional calculus of -contractions
Felix L. Schwenninger, Jens de Vries
Let be a -contraction and a rational function mapping the closed unit disk into itself. With a new characterization of -contractions we prove that \begin{align*} \big…
BIBO stability of 1-D hyperbolic boundary control systems
Felix L. Schwenninger, Alexander A. Wierzba
We study the question of bounded-input bounded-output (BIBO) stability of a class of 1-D hyperbolic boundary control systems, which, in particular, contains distributed port-Hamilt…
The algebraic numerical range as a spectral set in Banach algebras
Hanna Blazhko, Daniil Homza, Felix L. Schwenninger +2
We investigate when the algebraic numerical range is a -spectral set in a Banach algebra. While providing several counterexamples based on classical ideas as well as combinatori…
A universal example for quantitative semi-uniform stability
Sahiba Arora, Felix Schwenninger, Ingrid Vukusic +1
We characterise quantitative semi-uniform stability for -semigroups arising from port-Hamiltonian systems, complementing recent works on exponential and strong stability. With…
The double-layer potential for spectral constants revisited
F. L. Schwenninger, J. de Vries
We thoroughly analyse the double-layer potential's role in approaches to spectral sets in the spirit of Delyon--Delyon, Crouzeix and Crouzeix--Palencia. While the potential is well…
A dual notion to BIBO stability
Felix L. Schwenninger, Alexander A. Wierzba
In this paper we consider BIBO stability of infinite-dimensional linear state-space systems and the related notion of -to- input-output stability (abbreviated LILO). We s…
Continuous maximal regularity in locally convex spaces
Karsten Kruse, Felix L. Schwenninger
We study maximal regularity with respect to continuous functions for strongly continuous semigroups on locally convex spaces as well as its relation to the notion of admissible ope…
Admissible operators for sun-dual semigroups
Sahiba Arora, Felix L. Schwenninger
We extend classical duality results by Weiss on admissible operators to settings where the dual semigroup lacks strong continuity. This is possible using the sun-dual framework, wh…
On checking -admissibility for parabolic control systems
Philip Preußler, Felix L. Schwenninger
In this note we discuss the difficulty of verifying -admissibility for -- that even manifests in the presence of a self-adjoint semigroup generator on a Hil…
The lattice structure of negative Sobolev and extrapolation spaces
Sahiba Arora, Jochen Glück, Felix L. Schwenninger
It is well-known that the Sobolev spaces are vector lattices with respect to the pointwise almost everywhere order if , but not if .…
Limit-case admissibility for positive infinite-dimensional systems
Sahiba Arora, Jochen Glück, Lassi Paunonen +1
In the context of positive infinite-dimensional linear systems, we systematically study -admissible control and observation operators with respect to the limit-cases $p=\infty…
Embeddings between Barron spaces with higher order activation functions
Tjeerd Jan Heeringa, Len Spek, Felix Schwenninger +1
The approximation properties of infinitely wide shallow neural networks heavily depend on the choice of the activation function. To understand this influence, we study embeddings b…
On BIBO stability of infinite-dimensional linear state-space systems
Felix L. Schwenninger, Alexander A. Wierzba, Hans Zwart
In this paper we consider BIBO stability of systems described by infinite-dimensional linear state-space representations, filling the so far unattended gap of a formal definition a…
Coercive quadratic converse ISS Lyapunov theorems for linear analytic systems
Andrii Mironchenko, Felix Schwenninger
We derive converse Lyapunov theorems for input-to-state stability (ISS) of linear infinite-dimensional analytic systems. While we show that ISS in general does not imply the existe…
Input-to-state stability for bilinear feedback systems
René Hosfeld, Birgit Jacob, Felix Schwenninger +1
Input-to-state stability estimates with respect to small initial conditions and input functions for infinite-dimensional systems with bilinear feedback are shown. We apply the obta…
BIBO stability for funnel control: semilinear internal dynamics with unbounded input and output operators
Anthony Hastir, René Hosfeld, Felix L. Schwenninger +1
This note deals with Bounded-Input-Bounded-Output (BIBO) stability for semilinear infinite-dimensional dynamical systems allowing for boundary control and boundary observation. We…
On Abstract Spectral Constants
Felix L. Schwenninger, Jens de Vries
We prove bounds for a class of unital homomorphisms arising in the study of spectral sets, by involving extremal functions and vectors. These are used to recover three celebrated r…
On the unique solvability of radiative transfer equations with polarization
Vincent Bosboom, Matthias Schlottbom, Felix Schwenninger
We investigate the well-posedness of the radiative transfer equation with polarization and varying refractive index. The well-posedness analysis includes non-homogeneous boundary v…
Sun dual theory for bi-continuous semigroups
Karsten Kruse, Felix L. Schwenninger
The sun dual space corresponding to a strongly continuous semigroup is a known concept when dealing with dual semigroups, which are in general only weak-continuous. In this pap…
Characterization of Orlicz admissibility
René Hosfeld, Birgit Jacob, Felix L. Schwenninger
In this note we extend two characterizations of admissible operators with respect to to more general Orlicz spaces. The equivalent conditions are given by the proper…
On equicontinuity and tightness of bi-continuous semigroups
Karsten Kruse, Felix L. Schwenninger
In contrast to classical strongly continuous semigroups, the study of bi-continuous semigroups comes with some freedom in the properties of the associated locally convex topology.…
Laplace-Carleson embeddings and infinity-norm admissibility
Birgit Jacob, Jonathan R. Partington, Sandra Pott +2
A full characterization of the boundedness of Laplace--Carleson embeddings on is provided, in terms of the Carleson intensity of the respective measure and of a suitable…