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Related papers: A Bloch-Landau Theorem for slice regular functions

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The aim of this work is to define a continuous functional calculus in quaternionic Hilbert spaces, starting from basic issues regarding the notion of spherical spectrum of a normal operator. As properties of the spherical spectrum suggest,…

Functional Analysis · Mathematics 2013-06-17 Riccardo Ghiloni , Valter Moretti , Alessandro Perotti

Recently, we introduced domains of slice regularity in the space $\mathbb{H}$ of quaternions and also proved that domains of slice regularity satisfy a symmetry with respect to paths, called $2$-path-symmetry. In this paper, we give a full…

Complex Variables · Mathematics 2024-05-07 Xinyuan Dou , Ming Jin , Guangbin Ren , Irene Sabadini

We prove that, for any closed semialgebraic subset $W$ of $\mathbb{R}^n$ and for any positive integer $p$, there exists a Nash function $f:\mathbb{R}^n\setminus W\longrightarrow (0, \infty)$ which is equivalent to the distance function from…

Classical Analysis and ODEs · Mathematics 2024-04-22 Beata Kocel-Cynk , Wiesław Pawłucki , Anna Valette

We prove the following theorem: let $\widetilde{\mathcal R}$ be an expansion of the real field $\overline{\mathbb R}$, such that every definable set (I) is a uniform countable union of semialgebraic sets, and (II) contains a "semialgebraic…

Logic · Mathematics 2018-12-27 Pantelis E. Eleftheriou , Alex Savatovsky

In this paper, we investigate holomorphic mappings $F$ on the unit ball $\mathbb{B}$ of a complex Banach space of the form $F(x)=f(x)x$, where $f$ is a holomorphic function on $\mathbb{B}$. First, we investigate criteria for univalence,…

Complex Variables · Mathematics 2024-09-09 Hidetaka Hamada , Gabriela Kohr , Mirela Kohr

Let $\mathcal{H}$ be the class of all complex-valued harmonic mappings $f=h+\overline{g}$ defined on the unit disc $\mathbb{D}=\{z\in\mathbb{C}:|z|<1\}$ with the normalization $h(0)=0=h'(0)-1$, here $h$ and $g$ are analytic functions in…

Complex Variables · Mathematics 2026-04-01 Molla Basir Ahamed , Rajesh Hossain

Entire functions in one complex variable are extremely relevant in several areas ranging from the study of convolution equations to special functions. An analog of entire functions in the quaternionic setting can be defined in the slice…

Complex Variables · Mathematics 2016-11-08 Fabrizio Colombo , Irene Sabadini , Daniele C. Struppa

The purpose of this paper is to present several new, sometimes surprising, results concerning a class of hyperholomorphic functions over quaternions, the so-called slice regular functions. The concept of slice regular function is a…

Complex Variables · Mathematics 2022-04-26 Riccardo Ghiloni , Alessandro Perotti

The space of Bloch functions on bounded symmetric domains is extended by considering Bloch functions $f$ on the unit ball $B_E$ of finite and infinite dimensional complex Banach spaces in two different ways: by extending the classical Bloch…

Functional Analysis · Mathematics 2018-02-23 Alejandro Miralles

In this paper we develop a theory of slice regular functions on a real alternative algebra $A$. Our approach is based on a well--known Fueter's construction. Two recent function theories can be included in our general theory: the one of…

Complex Variables · Mathematics 2018-07-02 Riccardo Ghiloni , Alessandro Perotti

We present some new relations between the Cauchy-Riemann operator on the real Clifford algebra $\mathbb R_n$ of signature $(0,n)$ and slice-regular functions on $\mathbb R_n$. The class of slice-regular functions, which comprises all…

Complex Variables · Mathematics 2022-04-26 Alessandro Perotti

The aim of this paper is to extend the so called slice analysis to a general case in which the codomain is a real vector space of even dimension, i.e. is of the form $\mathbb{R}^{2n}$. We define a cone $\mathcal{W}_\mathcal{C}^d$ in…

Complex Variables · Mathematics 2024-01-05 Xinyuan Dou , Guangbin Ren , Irene Sabadini

In the present article, we investigate the univalence property of polyanalytic functions and $\log$-$\alpha$-analytic functions. First, by using a new idea, we prove an improved lemma and the coefficient estimates for bounded polyanalytic…

Complex Variables · Mathematics 2025-10-06 P. Li , M. -S. Liu , S. Ponnusamy , H. Zhao

UNIFORM algebras have been extensively investigated because of their importance in the theory of uniform approximation and as examples of complex Banach algebras. An interesting question is whether analogous algebras exist when a complete…

Functional Analysis · Mathematics 2012-01-31 Jonathan W. Mason

In this paper, we lay the foundations of the theory of slice regular functions in several variables ranging in any real alternative $^*$-algebra, including quaternions, octonions and Clifford algebras. This theory is an extension of the…

Complex Variables · Mathematics 2023-10-16 Riccardo Ghiloni , Alessandro Perotti

We prove the existence of functions $f$ in the Bloch space of the unit ball $\mathbb{B}_N$ of $\mathbb{C}^N$ with the property that, given any measurable function $\varphi$ on the unit sphere $\mathbb{S}_N$, there exists a sequence…

Complex Variables · Mathematics 2024-07-12 Stéphane Charpentier , Nicolas Espoullier , Rachid Zarouf

In this paper we summarize some known facts on slice topology in the quaternionic case, and we deepen some of them by proving new results and discussing some examples. We then show, following [18], how this setting allows us to generalize…

Complex Variables · Mathematics 2024-06-27 X. Dou , M. Jin , G. Ren , I. Sabadini

The purpose of this paper is to develop the theory of holomorphic functions with modulus bounded by $1$ on the symmetrized skew bidisc \[ \mathbb{G}_{r} \stackrel{\rm def}{=} \Big\{( \lambda_{1}+r\lambda_{2} ,r\lambda_{1}\lambda_{2}):…

Complex Variables · Mathematics 2026-03-31 Connor Evans , Zinaida A. Lykova , N. J. Young

Under very general conditions it is shown that if $A$ is a uniform algebra generated by real-analytic functions, then either $A$ consists of all continuous functions or else there exists a disc on which every function in $A$ is holomorphic.…

Complex Variables · Mathematics 2017-10-10 Alexander J. Izzo

The aim of this paper is to provide and prove the most general Cauchy integral formula for slice regular functions and for C^1 functions on a real alternative *-algebra. Slice regular functions represent a generalization of the classical…

Complex Variables · Mathematics 2016-02-12 Riccardo Ghiloni , Alessandro Perotti , Vincenzo Recupero