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We develop an operator-theoretic approach to quaternionic Fock spaces, with emphasis on Carleson measures, Berezin transforms, and Toeplitz operators. We first introduce a global Gaussian $L^p$-framework on $\mathbb H$ for slice functions…

Functional Analysis · Mathematics 2026-03-24 Zhaopeng Lin , Yufeng Lu , Chao Zu

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

The recent definition of slice regular function of several quaternionic variables suggests a new notion of quaternionic manifold. We give the definition of quaternionic regular manifold, as a space locally modeled on $\mathbb{H}^n$, in a…

Complex Variables · Mathematics 2016-12-13 Graziano Gentili , Anna Gori , Giulia Sarfatti

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 develop a functional calculus for bounded operators defined on quaternionic Banach spaces. This calculus is based on the notion of slice-regularity, see \cite{gs}, and the key tools are a new resolvent operator and a new…

Spectral Theory · Mathematics 2010-03-30 F. Colombo , G. Gentili , I. Sabadini , D. C. Struppa

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

Given a quaternionic slice regular function $f$, we give a direct and effective way to compute the coefficients of its spherical expansion at any point. Such coefficients are obtained in terms of spherical and slice derivatives of the…

Complex Variables · Mathematics 2021-12-22 Amedeo Altavilla

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

A quaternionic matrix-valued regular function is a map $F: \Omega \rightarrow M_n(\mathbb{H})$ whose entries are (left) regular functions of a quaternion variable, where $\Omega$ is a domain in $\mathbb{H}$. Our aim is to bring out some…

Functional Analysis · Mathematics 2026-02-18 Sachindranath Jayaraman , Dhashna T. Pillai

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

Based on a new generalization of Cauchy-Riemann system presented in this paper, we introduce a class of quaternion-valued functions of a quaternionic variable, which are called algebraic regular functions. The set of algebraic regular…

Complex Variables · Mathematics 2015-11-30 Keqin Liu

We prove a Slice Theorem around closed leaves in a singular Riemannian foliation, and we use it to study the $C^\infty$-algebra of smooth basic functions, generalizing to the inhomogeneous setting a number of results by G.~Schwarz. In…

Differential Geometry · Mathematics 2018-02-16 Ricardo Mendes , Marco Radeschi

we start the study of Schur analysis in the quaternionic setting using the theory of slice hyperholomorphic functions. The novelty of our approach is that slice hyperholomorphic functions allows to write realizations in terms of a suitable…

Functional Analysis · Mathematics 2011-10-13 Daniel Alpay , Fabrizio Colombo , Irene Sabadini

In this paper we introduce the notion of slice regular right linear semigroup in a quaternionic Banach space. It is an operatorial function which is slice regular (a noncommutative counterpart of analyticity) and which satisfies a…

Functional Analysis · Mathematics 2016-05-19 Riccardo Ghiloni , Vincenzo Recupero

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

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

In this paper we prove a quaternionic positive real lemma as well as its generalized version, in case the associated kernel has negative squares for slice hyperholomorphic functions. We consider the case of functions with positive real part…

Complex Variables · Mathematics 2018-10-16 D. Alpay , F. Colombo , I. Lewkowicz , I. Sabadini

The primary objective of this paper is to establish an algebraic framework for the space of weakly slice regular functions over several quaternionic variables. We recently introduced a $*$-product that maintains the path-slice property…

Complex Variables · Mathematics 2025-01-16 Xinyuan Dou , Ming Jin , Guangbin Ren , Ting Yang

We study various aspects of Schur analysis in the slice hyperholomorphic setting. We present two sets of results: first, we give new results on the functional calculus for slice hyperholomorphic functions. In particular, we introduce and…

Functional Analysis · Mathematics 2012-11-14 Daniel Alpay , Fabrizio Colombo , Irene Sabadini

A slice regular analogue of the Malmquist-Takenaka system is investigated. It is proved that they form a complete orthonormal system in the quaternionic Hardy spaces of the unit ball. The properties of associated projection operator are…

Complex Variables · Mathematics 2016-11-21 Margit Pap