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We introduce Wirtinger operators for functions of several quaternionic variables. These operators are real linear partial differential operators which behave well on quaternionic polynomials, with properties analogous to the ones satisfied…

Complex Variables · Mathematics 2024-11-13 Alessandro Perotti

The analogous quaternionic polynomials of a class of bivariate orthogonal polynomials (arXiv: 1502.07256, 2014) introduced. The ladder operators for these quaternionic polynomials also studied. For the quaternionic case, the ladder…

Mathematical Physics · Physics 2015-07-01 Nasser Saad , K. Thirulogasanthar

A promising theory of quaternion-valued functions of one quaternionic variable, now called slice regular functions, has been introduced in 2006. The basic examples of slice regular functions are power series centered at 0 on their balls of…

Complex Variables · Mathematics 2012-09-11 Caterina Stoppato

Quaternionic analysis relies heavily on results on functions defined on domains in $\mathbb R^4$ (or $\mathbb R^3$) with values in $\mathbb H$. This theory is centered around the concept of $\psi-$hyperholomorphic functions i.e.,…

Complex Variables · Mathematics 2022-09-27 José Oscar González-Cervantes , Juan Bory-Reyes

After Gentili and Struppa introduced in 2006 the theory of quaternionic slice regular function, the theory has focused on functions on the so-called slice domains. The present work defines the class of speared domains, which is a rather…

Complex Variables · Mathematics 2024-06-10 Riccardo Ghiloni , Caterina Stoppato

New universal invariant operators are introduced in a class of geometries which include the quaternionic structures and their generalisations as well as 4-dimensional conformal (spin) geometries. It is shown that, in a broad sense, all…

Differential Geometry · Mathematics 2009-10-31 A. R. Gover , J. Slovak

The goal of this paper is to introduce and study some geometric properties of slice regular functions of quaternion variable like univalence, subordination, starlikeness, convexity and spirallikeness in the unit ball. We prove a number of…

Complex Variables · Mathematics 2014-10-13 Sorin G. Gal , J. Oscar González-Cervantes , Irene Sabadini

The purpose of this paper is to develop a new theory of three non-commuting quaternionic variables and its related Schur analysis theory for a modified version of the quaternionic global operator.

Complex Variables · Mathematics 2022-12-13 Daniel Alpay , Kamal Diki , Mihaela Vajiac

In this paper we extend the $H^\infty$ functional calculus to quaternionic operators and to $n$-tuples of noncommuting operators using the theory of slice hyperholomorphic functions and the associated functional calculus, called…

Functional Analysis · Mathematics 2015-11-25 D. Alpay , F. Colombo , T. Qian , I. Sabadini

In this article, we present the symmetry group of a global slice Dirac operator and its iterated ones. Further, the explicit forms of intertwining operators of the iterated global slice Dirac operator are given. At the end, we introduce a…

Complex Variables · Mathematics 2024-09-17 Chao Ding , Zhenghua Xu

For quaternionic signal processing algorithms, the gradients of a quaternion-valued function are required for gradient-based methods. Given the non-commutativity of quaternion algebra, the definition of the gradients is non-trivial. The HR…

Optimization and Control · Mathematics 2014-07-22 Mengdi Jiang , Yi Li , Wei Liu

The concept of slice regular function over the real algebra $\mathbb{H}$ of quaternions is a generalization of the notion of holomorphic function of a complex variable. Let $\Omega$ be an open subset of $\mathbb{H}$, which intersects…

Complex Variables · Mathematics 2020-11-20 Riccardo Ghiloni

In this paper we describe the rise of global operators in the scaled quaternionic case, an important extension from the quaternionic case to the family of scaled hypercomplex numbers $\mathbb{H}_t,\, t\in\mathbb{R}^*$, of which the…

Functional Analysis · Mathematics 2024-04-05 Daniel Alpay , Ilwoo Cho , Mihaela Vajiac

This paper addresses particular eigenvalue problems within the context of two quaternionic function theories. More precisely, we study two concrete classes of quaternionic eigenvalue problems, the first one for the slice derivative operator…

Complex Variables · Mathematics 2023-10-16 Rolf Sören Krausshar , Alessandro Perotti

Slice regular functions have been extensively studied over the past decade, but much less is known about their boundary behavior. In this paper, we initiate the study of Julia theory for slice regular functions. More specifically, we…

Complex Variables · Mathematics 2016-03-22 Guangbin Ren , Xieping Wang

In this paper we characterize the closed invariant subspaces for the ($*$-)multiplier operator of the quaternionic space of slice $L^2$ functions. As a consequence, we obtain the inner-outer factorization theorem for the quaternionic Hardy…

Complex Variables · Mathematics 2018-06-13 Alessandro Monguzzi , Giulia Sarfatti

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

The main goal of this work is classifying the singularities of slice regular functions over a real alternative *-algebra A. This function theory has been introduced in 2011 as a higher-dimensional generalization of the classical theory of…

Complex Variables · Mathematics 2017-03-16 Riccardo Ghiloni , Alessandro Perotti , Caterina Stoppato

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

The two function theories of monogenic and of slice monogenic functions have been extensively studied in the literature and were developed independently; the relations between them, e.g. via Fueter mapping and Radon transform, have been…

Complex Variables · Mathematics 2024-12-19 Zhenghua Xu , Irene Sabadini