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The theory of slice regular functions of a quaternionic variable, introduced in 2006 by Gentili and Struppa, extends the notion of holomorphic function to the quaternionic setting. This fast growing theory is already rich of many results…

Complex Variables · Mathematics 2015-03-17 Chiara de Fabritiis , Graziano Gentili , Giulia Sarfatti

This work looks at the theory of octonionic slice regular functions through the lens of differential topology. It proves a full-fledged version of the Open Mapping Theorem for octonionic slice regular functions. Moreover, it opens the path…

Complex Variables · Mathematics 2022-10-13 Riccardo Ghiloni , Alessandro Perotti , Caterina Stoppato

This work studies slice functions over finite-dimensional division algebras. Their zero sets are studied in detail along with their multiplicative inverses, for which some unexpected phenomena are discovered. The results are applied to…

Complex Variables · Mathematics 2020-07-15 Riccardo Ghiloni , Alessandro Perotti , Caterina Stoppato

Two themes drive this article: identifying the structure necessary to formulate quaternionic operator theory and revealing the relation between complex and quaternionic operator theory. The theory of quaternionic right linear operators is…

Spectral Theory · Mathematics 2018-03-29 Jonathan Gantner

We introduce a class of rings using which we define the concept of skew regularity for quaternion-valued functions over quaternions. It is shown that the notion of skew regularity coincides with the concept of slice regularity over…

Rings and Algebras · Mathematics 2022-11-15 Masood Aryapoor

In this paper, we define the quaternionic Fock spaces $\mathfrak{F}_{\alpha}^p$ of entire slice hyperholomorphic functions in a quaternionic unit ball $\mathbb{B}$ in $\mathbb{H}.$ We also study growth estimate and various results of entire…

Functional Analysis · Mathematics 2016-11-17 Sanjay Kumar , S. D. Sharma , Khalid Manzoor

The aim of this paper is to prove that a large class of quaternionic slice regular functions result to be (ramified) covering maps. By means of the topological implications of this fact and by providing further topological structures, we…

Complex Variables · Mathematics 2022-06-07 Amedeo Altavilla , Samuele Mongodi

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

In this paper we show that the real differential of any injective slice regular function is everywhere invertible. The result is a generalization of a theorem proved by G. Gentili, S. Salamon and C. Stoppato, and it is obtained thanks, in…

Complex Variables · Mathematics 2019-01-03 Amedeo Altavilla

The celebrated 100-year old Phragmen-Lindelof principle is a far reaching extension of the maximum modulus theorem for holomorphic functions of one complex variable. In some recent papers there has been a resurgence of interest in…

Complex Variables · Mathematics 2022-09-07 G. Gentili , C. Stoppato , D. C. Struppa

In this paper we study some fundamental algebraic properties of slice functions and slice regular functions over an alternative $^*$-algebra $A$ over $\mathbb{R}$. These recently introduced function theories generalize to higher dimensions…

Complex Variables · Mathematics 2017-11-20 Riccardo Ghiloni , Alessandro Perotti , Caterina Stoppato

We prove a Cauchy-type integral formula for slice-regular functions where the integration is performed on the boundary of an open subset of the quaternionic space, with no requirement of axial symmetry. In particular, we get a local…

Complex Variables · Mathematics 2023-10-16 Alessandro Perotti

The regular fractional transformations of the extended quaternionic space have been recently introduced as variants of the classical linear fractional transformations. These variants have the advantage of being included in the class of…

Complex Variables · Mathematics 2013-02-12 Cinzia Bisi , Caterina Stoppato

In this paper we propose an Almansi-type decomposition for slice regular functions of several quaternionic variables. Our method yields $2^n$ distinct and unique decompositions for any slice function with domain in $\mathbb{H}^n$. Depending…

Complex Variables · Mathematics 2024-11-12 Giulio Binosi

In this paper we prove a new version of Krein-Langer factorization theorem in the slice hyperholomorphic setting which is more general than the one proved in [D. Alpay, F. Colombo, I. Sabadini, Krein-Langer factorization and related topics…

Complex Variables · Mathematics 2014-06-27 Daniel Alpay , Fabrizio Colombo , Irene Sabadini

We study global properties of quaternionic slice regular functions (also called s-regular) defined on symmetric slice domains. In particular, thanks to new techniques and points of view, we can characterize the property of being one-slice…

Complex Variables · Mathematics 2019-01-03 Amedeo Altavilla , Chiara de Fabritiis

In this paper, we prove that slice polyanalytic functions on quaternions can be considered as solutions of a power of some special global operator with nonconstant coefficients as it happens in the case of slice hyperholomorphic functions.…

Complex Variables · Mathematics 2021-01-06 Daniel Alpay , Kamal Diki , Irene Sabadini

In this paper we prove a new representation formula for slice regular functions, which shows that the value of a slice regular function $f$ at a point $q=x+yI$ can be recovered by the values of $f$ at the points $q+yJ$ and $q+yK$ for any…

Complex Variables · Mathematics 2010-03-30 Fabrizio Colombo , Graziano Gentili , Irene Sabadini , Daniele C. Struppa

An important consequence of the Hahn-Banach Theorem says that on any locally convex Hausdorff topological space $X$, there are sufficiently many continuous linear functionals to separate points of $X$. In the paper, we establish a `local'…

Functional Analysis · Mathematics 2018-09-07 Niushan Gao , Denny H. Leung , Foivos Xanthos

This paper has a twofold purpose: on one hand we deepen the study of slice regular functions by studying their behavior with respect to the so-called C-property and anti-C-property. We show that, for any fixed basis of the algebra of…

Complex Variables · Mathematics 2014-06-24 Fabrizio Colombo , J. Oscar Gonzales-Cervantes