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The theory of slice regular functions of a quaternionic variable extends the notion of holomorphic function to the quaternionic setting. This theory, already rich of results, is sometimes surprisingly different from the theory of…

Complex Variables · Mathematics 2014-04-14 Graziano Gentili , Giulia Sarfatti

Gramsch and Lay [10] gave spectral mapping theorems for the Dunford-Taylor calculus of a closed linear operator $T$, $$\widetilde{\sigma}_i(f(T)) = f(\widetilde{\sigma}_i(T)), $$ for several extended essential spectra…

Functional Analysis · Mathematics 2023-01-05 Jesús Oliva-Maza

We study bounded holomorphic functional calculus for nonsymmetric infinite dimensional Ornstein-Uhlenbeck operators ${\mathscr L}$. We prove that if $-{\mathscr L}$ generates an analytic semigroup on $L^{2}(\gamma_{\infty})$, then…

Functional Analysis · Mathematics 2016-09-13 Andrea Carbonaro , Oliver Dragičević

We study the functional calculus associated with a hypoelliptic left-invariant differential operator $\mathcal{L}$ on a connected and simply connected nilpotent Lie group $G$ with the aid of the corresponding \emph{Rockland} operator…

Functional Analysis · Mathematics 2021-04-13 Mattia Calzi , Fulvio Ricci

Slice analysis is a generalization of the theory of holomorphic functions of one complex variable to quaternions. Among the new phenomena which appear in this context, there is the fact that the convergence domain of…

Complex Variables · Mathematics 2021-01-26 Xinyuan Dou , Guangbin Ren , Irene Sabadini

Let ${\cal{M}}$ be a complete Riemannian manifold with Ricci curvature bounded below and Laplace operator $\Delta$. The paper develops a functional calculus for the cosine family $\cos(t\sqrt {\Delta})$ which is associated with waves that…

Functional Analysis · Mathematics 2015-09-07 Gordon Blower , Ian Doust

The slice Dirac operator over octonions is a slice counterpart of the Dirac operator over quaternions. It involves a new theory of stem functions, which is the extension from the commutative $ O(1) $ case to the non-commutative $ O(3) $…

Complex Variables · Mathematics 2019-12-11 Ming Jin , Guangbin Ren , Irene Sabadini

We study the product formula $(fg)(A) = f(A)g(A)$ in the framework of (unbounded) functional calculus of sectorial operators $A$. We give an abstract result, and, as corollaries, we obtain new product formulas for the holomorphic functional…

Functional Analysis · Mathematics 2014-09-30 Charles Batty , Alexander Gomilko , Yuri Tomilov

This note deals with the boundedness of the $H^\infty$ functional calculus of Ritt operators $T$ and associated square function estimates. The purpose is to give a shorter, concise and slightly more general approach towards Le~Merdy's…

Functional Analysis · Mathematics 2023-03-07 Bernhard H. Haak

We prove that the existence of a Mihlin-H\"ormander functional calculus for an operator $L$ implies the boundedness on $L^p$ of both the maximal operators and the continuous square functions build on spectral multipliers of $L.$ The…

Functional Analysis · Mathematics 2016-08-08 Błażej Wróbel

Let $X$ be a space of homogeneous type and let $L$ be a sectorial operator with bounded holomorphic functional calculus on $L^2(X)$. We assume that the semigroup $\{e^{-tL}\}_{t>0}$ satisfies Davies-Gaffney estimates. In this paper, we…

Functional Analysis · Mathematics 2011-07-22 Dorothee Frey

We develop a functional calculus for $d$-tuples of non-commuting elements in a Banach algebra. The functions we apply are free analytic functions, that is nc functions that are bounded on certain polynomial polyhedra.

Functional Analysis · Mathematics 2015-04-29 Jim Agler , John E. McCarthy

The functionals on an ordered semigroup S in the category Cu--a category to which the Cuntz semigroup of a C*-algebra naturally belongs--are investigated. After appending a new axiom to the category Cu, it is shown that the "realification"…

Operator Algebras · Mathematics 2014-01-07 Leonel Robert

This is a tutorial introduction to the functional analysis mathematics needed in many physical problems, such as in waves in continuous media. Functional analysis takes us beyond finite matrices, allowing us to work with infinite sets of…

Functional Analysis · Mathematics 2019-04-15 David A. B. Miller

In this paper we develop a new set of results based on a nonlocal gradient jointly inspired by the Riesz s-fractional gradient and Peridynamics, in the sense that its integration domain depends on a ball of radius delta > 0 (horizon of…

Analysis of PDEs · Mathematics 2022-11-07 José Carlos Bellido , Javier Cueto , Carlos Mora-Corral

In this paper, we develop a semi-classical analysis on H-type groups. We define semi-classical pseudodifferential operators, prove the boundedness of their action on square integrable functions and develop a symbolic calculus. Then, we…

Functional Analysis · Mathematics 2018-12-04 Clotilde Fermanian-Kammerer , Veronique Fischer

The theory of slice regular (also called hyperholomorphic) functions is a generalization of complex analysis originally given in the quaternionic framework, and then further extended to Clifford algebras, octonions, and to real alternative…

Complex Variables · Mathematics 2025-12-02 Xinyuan Dou , Ming Jin , Guangbin Ren , Irene Sabadini

In this work we treat realization results for operator-valued functions which are analytic in the complex sense or slice hyperholomorphic over the quaternions. In the complex setting, we prove a realization theorem for an operator-valued…

Functional Analysis · Mathematics 2018-04-17 Daniel Alpay , Fabrizio Colombo , Irene Sabadini

Given a real, symmetric matrix S, we define the slice through S as being the connected component containing S of two orbits under conjugation: the first by the orthogonal group, and the second by the upper triangular group. We describe some…

Rings and Algebras · Mathematics 2007-05-23 Ricardo S. Leite , Carlos Tomei

In this paper we study a class $\mathcal R\mathcal S(\mathfrak M)$ of operator functions that are holomorphic in the domain $\mathbb C\setminus\{(-\infty,-1]\cup [1,+\infty)\}$ and whose values are contractive operators in a Hilbert space…

Functional Analysis · Mathematics 2018-07-05 Yury Arlinski\uı , Seppo Hassi