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We prove sectorial extension theorems for ultraholomorphic function classes of Beurling type defined by weight functions with a controlled loss of regularity. The proofs are based on a reduction lemma, due to the second author, which allows…

Functional Analysis · Mathematics 2022-12-29 David Nicolas Nenning , Armin Rainer , Gerhard Schindl

We prove several extension theorems for Roumieu ultraholomorphic classes of functions in sectors of the Riemann surface of the logarithm which are defined by means of a weight function or weight matrix. Our main aim is to transfer the…

Functional Analysis · Mathematics 2019-08-20 Javier Jiménez-Garrido , Javier Sanz , Gerhard Schindl

The aim of this work is to generalize the ultraholomorphic extension theorems from V. Thilliez in the weight sequence setting and from the authors in the weight function setting (of Roumieu type) to a mixed framework. Such mixed results…

Complex Variables · Mathematics 2022-12-29 Javier Jiménez-Garrido , Javier Sanz , Gerhard Schindl

We survey ultradifferentiable extension theorems, i.e., quantitative versions of Whitney's classical extension theorem, with special emphasis on the existence of continuous linear extension operators. The focus is on Denjoy-Carleman classes…

Functional Analysis · Mathematics 2022-01-03 Armin Rainer

We answer a question from A. V. Abanin and P. T. Tien about so-called almost subadditive weight functions in the sense of Braun-Meise-Taylor. Using recent knowledge of a growth index for functions, crucially appearing in the…

Complex Variables · Mathematics 2024-07-26 Gerhard Schindl

We prove a version of Whitney's extension theorem in the ultradifferentiable Beurling setting with controlled loss of regularity. As a by-product we show the existence of continuous linear extension operators on certain spaces of Whitney…

Classical Analysis and ODEs · Mathematics 2021-01-08 Armin Rainer

We study and characterize the inclusion relations of global classes in the general weight matrix framework in terms of growth relations for the defining weight matrices. We consider the Roumieu and Beurling cases, and as a particular case…

Functional Analysis · Mathematics 2024-07-30 Chiara Boiti , David Jornet , Alessandro Oliaro , Gerhard Schindl

We prove several improved versions of the Borel-Ritt theorem about the surjectivity of the asymptotic Borel mapping in classes of functions with $\boldsymbol{M}$-uniform asymptotic expansion on an unbounded sector of the Riemann surface of…

Complex Variables · Mathematics 2025-05-15 Javier Jiménez-Garrido , Ignacio Miguel-Cantero , Javier Sanz , Gerhard Schindl

Given a compact of ${\bf R}^n$, there is always a doubling measure having it as its support. We use this fact to construct an integral operator that extends differentiable functions defined on any compact set of ${\bf R}^n$ to the whole of…

Classical Analysis and ODEs · Mathematics 2007-05-23 Jaume Gudayol

We prove in a uniform way that all ultradifferentiable function classes of Roumieu- and of Beurling-type defined in terms of a weight matrix admit a convenient setting if the matrix satisfies some mild regularity conditions. We prove that…

Functional Analysis · Mathematics 2016-03-03 Gerhard Schindl

We revisit Whitney's extension theorem in the ultradifferentiable Roumieu setting. Based on the description of ultradifferentiable classes by weight matrices, we extend results on how growth constraints on Whitney jets on arbitrary compact…

Classical Analysis and ODEs · Mathematics 2017-11-29 Armin Rainer , Gerhard Schindl

We introduce the new notion of a conjugate weight function and provide a detailed study of this operation and its properties. Then we apply this knowledge to study classes of ultradifferentiable functions defined in terms of fast growing…

Functional Analysis · Mathematics 2026-03-31 Gerhard Schindl

We give a complete solution to the Borel-Ritt problem in non-uniform spaces $\mathscr{A}^-_{(M)}(S)$ of ultraholomorphic functions of Beurling type, where $S$ is an unbounded sector of the Riemann surface of the logarithm and $M$ is a…

Functional Analysis · Mathematics 2020-11-17 Andreas Debrouwere

A theorem by Wolff states that weights defined on a measurable subset of $\mathbb{R}^n$ and satisfying a Muckenhoupt-type condition can be extended into the whole space as Muckenhoupt weights of the same class. We give a complete and…

Classical Analysis and ODEs · Mathematics 2021-10-26 Emma-Karoliina Kurki , Carlos Mudarra

We introduce a modified version of the Whitney extension operators for collections of functions from a closed subset of $\mathbb{R}^n$ into scales of Banach spaces with smoothing operators. We prove an extension theorem for collections…

Functional Analysis · Mathematics 2021-02-12 Pietro Baldi

We prove a Kotake-Narasimhan type theorem in general ultradifferentiable classes given by weight matrices. In doing so we simultaneously recover and partially generalize the known results for classes given by weight sequences and weight…

Analysis of PDEs · Mathematics 2025-01-23 Stefan Fürdös

We construct optimal flat functions in Carleman-Roumieu ultraholomorphic classes associated to general strongly nonquasianalytic weight sequences, and defined on sectors of suitably restricted opening. A general procedure is presented in…

Complex Variables · Mathematics 2023-06-05 Javier Jiménez-Garrido , Ignacio Miguel-Cantero , Javier Sanz , Gerhard Schindl

We provide a projective description of the space $\mathcal{E}^{\{\mathfrak{M}\}}(\Omega)$ of ultradifferentiable functions of Roumieu type, where $\Omega$ is an arbitrary open set in $\mathbb{R}^d$ and $\mathfrak{M}$ is a weight matrix…

Functional Analysis · Mathematics 2022-11-17 Andreas Debrouwere , Bojan Prangoski , Jasson Vindas

We consider classes $ \mathcal{A}_M(S) $ of functions holomorphic in an open plane sector $ S $ and belonging to a strongly non-quasianalytic class on the closure of $ S $. In $ \mathcal{A}_M(S) $, we construct functions which are flat at…

Classical Analysis and ODEs · Mathematics 2007-05-23 Vincent Thilliez

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
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