4 citations · 21 across the 27 of their papers we have counts for
28 papers
Fractional symplectic Fourier transforms and their actions on function and distribution spaces
Lenny Neyt, Joachim Toft
We consider symplectic analogues of the fractional Fourier transforms and obtain convenient representations in terms of Bargmann transforms and Wigner distributions. We show that t…
Spectral characterizations of stable operator semigroups
Morgan Callewaert, Lenny Neyt, Jasson Vindas
We introduce the notion of local pseudofunction spectrum for the infinitesimal generator of a bounded -semigroup on a Banach…
A Pełczyński-Vogt decomposition result for (PLS)-spaces and sequence space representations
Andreas Debrouwere, Lenny Neyt
We establish a Pelczyński-Vogt decomposition result for (PLS)-type power series spaces of infinite type. By combining this result with the theory of Gabor frames, we obtain sequenc…
Bornological LB-spaces and idempotent adjunctions
Jack Kelly, Lenny Neyt, Sven-Ake Wegner
The notion of an LB-space was introduced by Grothendieck in his 1953 thèse, referring to a countable colimit of Banach spaces taken within the category of locally convex topologica…
Sequence space representations of Beurling-Björck spaces via Gabor frames and Wilson bases
Andreas Debrouwere, Lenny Neyt
We establish sequence space representations of a broad class of Beurling-Björck spaces and . We develop two different approac…
Quantitative uncertainty principles for time-frequency Gaussian decay
Lenny Neyt, Joachim Toft, Jasson Vindas
For real symmetric positive definite matrices and , we characterize when a function satisfies \[ |f(x)| \lesssim e^{-(\frac12 - λ) \langle Ax, x\ra…
Optimal decay of semi-uniformly stable operator semigroups with empty spectrum
Morgan Callewaert, Lenny Neyt, Jasson Vindas
We show that it is impossible to quantify the decay rate of a semi-uniformly stable operator semigroup based on sole knowledge of the spectrum of its infinitesimal generator. More…
Weighted function spaces: convolutors, multipliers, and mollifiers
Lenny Neyt, Yoshihiro Sawano
We study smooth function spaces of Gelfand-Shilov type, with global behavior governed through a translation-invariant Banach function space and localized via a weight function syst…
On a space of functions with entire Laplace transforms and its connection with the optimality of the Ingham-Karamata theorem
Morgan Callewaert, Lenny Neyt, Jasson Vindas
We study approximation properties of the Fréchet space of all continuously differentiable functions such that and such that their Laplace transforms admit entire e…
On the inclusion relations between Gelfand-Shilov spaces
Andreas Debrouwere, Lenny Neyt, Jasson Vindas
We study inclusion relations between Gelfand-Shilov type spaces defined via a weight (multi-)sequence system, a weight function system, and a translation-invariant Banach function…
Hermite expansions for spaces of functions with nearly optimal time-frequency decay
Lenny Neyt, Joachim Toft, Jasson Vindas
We establish Hermite expansion characterizations for several subspaces of the Fréchet space of functions on the real line satisfying \begin{equation*} |f(x)| \lesssim e^{-(\frac{1}…
The vector-valued Stieltjes moment problem with general exponents
Andreas Debrouwere, Lenny Neyt
We characterize the sequences of complex numbers and the locally complete -spaces such that for each $(e_{n})_{n \in \mathbb{N}} \in E^\mathb…
An extension result for -spaces and the surjectivity of tensorized mappings
Andreas Debrouwere, Lenny Neyt
We study an extension problem for continuous linear maps in the setting of -spaces. More precisely, we characterize the pairs , where is a locally complete space w…
The global solvability of the Kirchhoff equation with Sobolev data
Tokio Matsuyama, Lenny Neyt
We consider linear and non-linear Cauchy equations in the context of Sobolev spaces. In particular, we show the global existence of solutions to the Kirchhoff equation with initial…
A note on the barrelledness of weighted -spaces of ultradifferentiable functions
Andreas Debrouwere, Lenny Neyt
In this note we consider weighted -spaces of ultradifferentiable functions defined via a weight function and a weight system, as introduced in our previous work [4]. We prov…
Kernel theorems for Beurling-Björck type spaces
Lenny Neyt, Jasson Vindas
We prove new kernel theorems for a general class of Beurling-Björck type spaces. In particular, our results cover the classical Beurling-Björck spaces and…
A note on composition operators between weighted spaces of smooth functions
Andreas Debrouwere, Lenny Neyt
For certain weighted locally convex spaces and of one real variable smooth functions, we characterize the smooth functions for which the comp…
A lower bound for the life span of solutions to the Kirchhoff equation with Gevrey data
Tokio Matsuyama, Lenny Neyt
We provide a new lower bound for the life span of solutions to the Kirchhoff equation for which the initial data belongs to the Gevrey space. This lower bound strictly improves the…
Sequence space representations for translation-modulation invariant function and distribution spaces
Andreas Debrouwere, Lenny Neyt
We provide sequence space representations for the test function space and the distribution space associated to a Banach space belon…
Explicit commutative sequence space representations of function and distribution spaces on the real half-line
Andreas Debrouwere, Lenny Neyt, Jasson Vindas
We provide explicit commutative sequence space representations for classical function and distribution spaces on the real half-line. This is done by evaluating at the Fourier trans…
Convolutors of translation-modulation invariant Banach spaces of ultradistributions
Lenny Neyt
We study the space of tempered ultradistributions whose convolutions with test functions are all contained in a given translation-modulation invariant Banach space of ultradistribu…
Weighted -spaces of ultradifferentiable functions and multiplier spaces
Andreas Debrouwere, Lenny Neyt
We study weighted -spaces of ultradifferentiable functions defined via a weight function (in the sense of Braun, Meise and Taylor) and a weight system. We characterize when…
The nuclearity of Gelfand-Shilov spaces and kernel theorems
Andreas Debrouwere, Lenny Neyt, Jasson Vindas
We study the nuclearity of the Gelfand-Shilov spaces and , defined via a weight (mu…
Characterization of nuclearity for Beurling-Björck spaces
Andreas Debrouwere, Lenny Neyt, Jasson Vindas
We characterize the nuclearity of the Beurling-Björck spaces and in terms of the defining weight…