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In this paper, we present an algebraic approach to idempotent functional analysis, which is an abstract version of idempotent analysis. The basic concepts and results are expressed in purely algebraic terms. We consider idempotent versions…

Functional Analysis · Mathematics 2007-05-23 Grigori Litvinov , Victor Maslov , Grigori Shpiz

Many possible definitions have been proposed for fractional derivatives and integrals, starting from the classical Riemann-Liouville formula and its generalisations and modifying it by replacing the power function kernel with other kernel…

Classical Analysis and ODEs · Mathematics 2021-05-03 Arran Fernandez , Mehmet Ali Ozarslan , Dumitru Baleanu

The $S$-functional calculus for slice hyperholomorphic functions generalizes the Riesz-Dunford-functional calculus for holomorphic functions to quaternionic linear operators and to $n$-tuples of noncommuting operators. For an unbounded…

Spectral Theory · Mathematics 2016-02-15 Jonathan Gantner

Joint spectra of tuples of operators are subsets in complex projective space. The corresponding tuple of operators can be viewed as an infinite dimensional analog of a determinantal representation of the joint spectrum. We investigate the…

Spectral Theory · Mathematics 2015-09-22 Michael Stessin , Alexandre Tchernev

We present a novel and unifying framework for constructing spectral approximations to fractional integral operators. These spectral approximations are based on transplanted Chebyshev polynomials, which are obtained by composing Chebyshev…

Numerical Analysis · Mathematics 2026-04-30 Xiaolin Liu , Kuan Xu

Recently, the conception of slice regular functions was allowed to introduce a new quaternionic functional calculus, among which the theory of semigroups of linear operators was developed into the quaternionic setting, even in a more…

Spectral Theory · Mathematics 2024-12-11 Qinghai Huo , Zhenghua Xu

In this paper we prove the spectral theorem for quaternionic unbounded normal operators using the notion of $S$-spectrum. The proof technique consists of first establishing a spectral theorem for quaternionic bounded normal operators and…

Spectral Theory · Mathematics 2014-12-18 Daniel Alpay , Fabrizio Colombo , David P. Kimsey

A complex-analytic structure within the unit disk of the complex plane is presented. It can be used to represent and analyze a large class of real functions. It is shown that any integrable real function can be obtained by means of the…

Complex Variables · Mathematics 2019-02-19 Jorge L. deLyra

There have been many proposed forms of fractional calculus, which can be grouped into a few broad classes of operators. By replacing the kernel of the power function with another kernel function, the traditional Riemann-Liouville formula…

Analysis of PDEs · Mathematics 2023-10-18 Erdal Gül , Ahmet Ocak Akdemir , Abdüllatif Yalçın

The foundation of spectral theory on the $S$-spectrum can be traced back to the quaternionic framework of quantum mechanics. The concept of $S$-spectrum for quaternionic operators emerged as the natural spectrum in slice hyperholomorphic…

Spectral Theory · Mathematics 2026-02-05 Francesco Mantovani

We use the fermionic construction of two-matrix model partition functions to evaluate integrals over rational symmetric functions. This approach is complementary to the one used in the paper ``Integrals of Rational Symmetric Functions,…

Mathematical Physics · Physics 2009-02-19 John Harnad , Alexander Yu. Orlov

We develop a holomorphic functional calculus for (multivalued linear) operators on locally convex vector spaces. This includes the case of fractional powers along Lipschitz curves.

Functional Analysis · Mathematics 2013-05-31 Gyula Lakos

In 2016, the spectral theory on the $S$-spectrum was used to establish the $H^\infty$-functional calculus for quaternionic or Clifford operators. This calculus applies for example to sectorial or bisectorial right linear operators $T$ and…

Spectral Theory · Mathematics 2025-05-06 Fabrizio Colombo , Francesco Mantovani , Peter Schlosser

We propose a framework for bilinear multiplier operators defined via the (bivariate) spectral theorem. Under this framework we prove Coifman-Meyer type multiplier theorems and fractional Leibniz rules. Our theory applies to bilinear…

Functional Analysis · Mathematics 2016-09-06 Błażej Wróbel

A unified approach is given to kernel functions which intertwine Ruijsenaars difference operators of type A and of type BC. As an application of the trigonometric cases, new explicit formulas for Koornwinder polynomials attached to single…

Quantum Algebra · Mathematics 2009-05-17 Yasushi Komori , Masatoshi Noumi , Jun'ichi Shiraishi

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

This article gives a fundamental discussion on variable coefficients, self-adjoint, formally partially hypoelliptic differential operators. A generalization of the results to pseudo differential operators, is given in a following article in…

Analysis of PDEs · Mathematics 2015-08-04 Tove Dahn

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

In this paper, we introduce the quaternionic slice polyanalytic functions and we prove some of their properties. Then, we apply the obtained results to begin the study of the quaternionic Fock and Bergman spaces in this new setting. In…

Complex Variables · Mathematics 2021-03-16 Daniel Alpay , Kamal Diki , Irene Sabadini

This paper contributes to the recently introduced theory of fine structures on the $S$-spectrum. We study, in a unified way, the functional calculi for axially Poly-Analytic-Harmonic functions on the $S$-spectrum. Axially…

Functional Analysis · Mathematics 2026-02-05 F. Colombo , A. De Martino , S. Pinton