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In this paper we give a global characterisation of classes of ultradifferentiable functions and corresponding ultradistributions on a compact manifold $X$. The characterisation is given in terms of the eigenfunction expansion of an elliptic…

Functional Analysis · Mathematics 2016-01-12 Aparajita Dasgupta , Michael Ruzhansky

We derive new results on the characterization of Gelfand--Shilov spaces $\mathcal{S}^\mu_\nu (\R^n)$, $\mu,\nu >0$, $\mu+\nu \geq 1$ by Gevrey estimates of the $L^2$ norms of iterates of $(m,k)$ anisotropic globally elliptic Shubin (or…

Functional Analysis · Mathematics 2016-09-21 Marco Cappiello , Todor Gramchev , Stevan Pilipovic , Luigi Rodino

We study function spaces consisting of analytic functions with fast decay on horizontal strips of the complex plane with respect to a given weight function. Their duals, so called spaces of (ultra)hyperfunctions of fast growth, generalize…

Functional Analysis · Mathematics 2018-07-11 Andreas Debrouwere , Jasson Vindas

We study the most general class of eigenfunction expansions for abstract normal operators with pure point spectrum in a complex Hilbert space. We find sufficient conditions for such expansions to be unconditionally convergent in spaces with…

Functional Analysis · Mathematics 2026-01-14 Vladimir Mikhailets , Aleksandr Murach

We define and characterize ultradifferentiable functions and their corresponding ultradistributions on $\RR^d_+$ using iterates of the Laguerre operator. The characterization is based on decay or growth conditions of the coefficients in…

Functional Analysis · Mathematics 2024-10-18 Smiljana Jakšić , Stevan Pilipović , Nenad Teofanov , Đorđe Vučković

In this paper we analyse the structure of the spaces of smooth type functions, generated by elements of arbitrary Hilbert spaces, as a continuation of the research in our previous papers in this series. We prove that these spaces are…

Functional Analysis · Mathematics 2018-12-05 Aparajita Dasgupta , Michael Ruzhansky

In this paper we analyse the structure of the spaces of coefficients of eigenfunction expansions of functions in Komatsu classes on compact manifolds, continuing the research in our previous paper. We prove that such spaces of Fourier…

Functional Analysis · Mathematics 2017-07-14 Aparajita Dasgupta , Michael Ruzhansky

We consider an arbitrary selfadjoint operator on a separable Hilbert space. To this operator we construct an expansion in generalized eigenfunctions in which the original Hilbert space is decomposed as a direct integral of Hilbert spaces…

Spectral Theory · Mathematics 2018-06-29 Daniel Lenz , Alexander Teplyaev

Spaces of infinitely differentiable functions on ${\mathbb R}^n$ (more general than Gelfand-Shilov spaces of type $W_M$) are considered in the article. Paley-Wiener type theorems are obtained.

Functional Analysis · Mathematics 2019-11-15 I. Kh. Musin

We prove rapid decay (even exponential decay under some stronger assumptions) of the eigenfunctions associated to discrete eigenvalues, for a class of self-adjoint operators in $L^2(\mathbb{R}^d)$ defined by ``magnetic'' pseudodifferential…

Analysis of PDEs · Mathematics 2013-04-10 Viorel Iftimie , Radu Purice

In the first part we analyze space $\mathcal G^*(\mathbb R^{n}_+)$ and its dual through Laguerre expansions when these spaces correspond to a general sequence $\{M_p\}_{p\in\mathbb N_0}$, where $^*$ is a common notation for the Beurling and…

Functional Analysis · Mathematics 2024-08-06 Stevan Pilipović , Đorđe Vučković

In the first part of the paper the authors study the minimal and maximal extension of a class of weighted pseudodifferential operators in the Fr\'echet space $L^p_{\rm loc}(\Omega)$. In the second one non homogeneous microlocal properties…

Analysis of PDEs · Mathematics 2014-12-24 Gianluca Garello , Alessandro Morando

For any bounded, regulated function $m: [0,\infty) \to \mathbb{C}$, consider the family of operators $\{ T_R \}$ on the sphere $S^d$ such that $T_R f = m(k/R) f$ for any spherical harmonic $f$ of degree $k$. We completely characterize the…

Classical Analysis and ODEs · Mathematics 2024-11-01 Jacob Denson

We consider time-frequency localization operators $A_a^{\varphi_1,\varphi_2}$ with symbols $a$ in the wide weighted modulation space $ M^\infty_{w}(\mathbb{R}^{2d})$, and windows $ \varphi_1, \varphi_2 $ in the Gelfand-Shilov space…

Functional Analysis · Mathematics 2020-04-29 Federico Bastianoni , Nenad Teofanov

In this note we consider weighted $(PLB)$-spaces of ultradifferentiable functions defined via a weight function and a weight system, as introduced in our previous work [4]. We provide a complete characterization of when these spaces are…

Functional Analysis · Mathematics 2022-08-31 Andreas Debrouwere , Lenny Neyt

We investigate H\"ormander spectral multiplier theorems as they hold on $X = L^p(\Omega),\: 1 < p < \infty,$ for many self-adjoint elliptic differential operators $A$ including the standard Laplacian on $\R^d.$ A strengthened matricial…

Classical Analysis and ODEs · Mathematics 2012-01-24 Christoph Kriegler

We study weighted $(PLB)$-spaces of ultradifferentiable functions defined via a weight function (in the sense of Braun, Meise and Taylor) and a weight system. We characterize when such spaces are ultrabornological in terms of the defining…

Functional Analysis · Mathematics 2022-01-11 Andreas Debrouwere , Lenny Neyt

This paper finishes the goal of the authors started in two previous manuscripts dedicated to revisiting the continuity properties of toroidal pseudo-differential operators with symbols in the H\"ormander classes. Here we prove pointwise…

Analysis of PDEs · Mathematics 2025-09-18 Duván Cardona , Manuel Alejandro Martínez

We discuss the structural and topological properties of a general class of weighted $L^1$ convolutor spaces. Our theory simultaneously applies to weighted $\mathcal{D}'_{L^1}$ spaces as well as to convolutor spaces of the Gelfand-Shilov…

Functional Analysis · Mathematics 2021-08-19 Andreas Debrouwere , Jasson Vindas

In this article, we develop a calculus of Shubin type pseudodifferential operators on certain non-compact spaces, using a groupoid approach similar to the one of van Erp and Yuncken. More concretely, we consider actions of graded Lie groups…

Analysis of PDEs · Mathematics 2025-01-13 Eske Ewert , Philipp Schmitt
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