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Semi-free ideal rings, or semifirs, were introduced by Paul M. Cohn to study universal localizations in the non-commutative setting. We provide new examples of semifirs consisting of analytic functions in several non-commuting variables.…

Operator Algebras · Mathematics 2025-12-02 Méric L. Augat , Robert T. W. Martin , Eli Shamovich

Noncommutative rational functions, i.e., elements of the universal skew field of fractions of a free algebra, can be defined through evaluations of noncommutative rational expressions on tuples of matrices. This interpretation extends their…

Rings and Algebras · Mathematics 2018-04-24 Jurij Volčič

Noncommutative functions are graded functions between sets of square matrices of all sizes over two vector spaces that respect direct sums and similarities. They possess very strong regularity properties (reminiscent of the regularity…

Functional Analysis · Mathematics 2020-05-20 Dmitry Kaliuzhnyi-Verbovetskyi , Leonard Stevenson , Victor Vinnikov

We define a free holomorphic function to be a function that is locally a bounded nc-function. We prove that free holomorphic functions are the functions that are locally uniformly approximable by free polynomials. We prove a realization…

Operator Algebras · Mathematics 2013-07-03 Jim Agler , John E. McCarthy

In the first half of twentieth century the theory of complex analytic functions and of their zerosets was fully developed. The definition of holomorphic function has a local nature. Germs of holomorphic functions form a distinguished…

Algebraic Geometry · Mathematics 2021-04-27 F. Acquistapace , F. Broglia , J. F. Fernando

This article, addressed to a general audience of functional analysts, is intended to be an illustration of a few basic principles from `noncommutative functional analysis', more specifically the new field of {\em operator spaces.} In our…

Functional Analysis · Mathematics 2007-05-23 David P. Blecher , Damon M. Hay

In this article we introduce powerful tools and techniques from invariant theory to free analysis. This enables us to study free maps with involution. These maps are free noncommutative analogs of real analytic functions of several…

Rings and Algebras · Mathematics 2019-08-15 Igor Klep , Špela Špenko

Let $X \overset{f}\longrightarrow S$ be a morphism of Noetherian schemes, with $S$ reduced. For any closed subscheme $Z$ of $X$ finite over $S$, let $j$ denote the open immersion $X\setminus Z \hookrightarrow X$. Koll\'ar asked whether for…

Algebraic Geometry · Mathematics 2016-07-04 Karen E Smith

This paper solves the rational noncommutative analog of Hilbert's 17th problem: if a noncommutative rational function is positive semidefinite on all tuples of hermitian matrices in its domain, then it is a sum of hermitian squares of…

Rings and Algebras · Mathematics 2021-08-23 Jurij Volčič

The classical theory of free analysis generalizes the noncommutative (nc) polynomials and rational functions, easily providing such results as an nc analogue of the Jacobian conjecture. However, the classical theory misses out on important…

Category Theory · Mathematics 2025-06-03 Julian Bushelli

One of the main applications of free probability is to show that for appropriately chosen independent copies of $d$ random matrix models, any noncommutative polynomial in these $d$ variables has a spectral distribution that converges…

Operator Algebras · Mathematics 2023-10-25 Benoît Collins , Tobias Mai , Akihiro Miyagawa , Félix Parraud , Sheng Yin

This paper investigates the interplay between local and global equivalences on noncommutative polynomials, the elements of the free algebra. When the latter are viewed as functions in several matrix variables, a local equivalence of…

Rings and Algebras · Mathematics 2025-05-13 Eli Shamovich , Jurij Volčič

This paper concerns free analytic maps on noncommutative domains. These maps are free analogs of classical holomorphic functions in several complex variables, and are defined in terms of noncommuting variables amongst which there are no…

Functional Analysis · Mathematics 2013-04-16 J. William Helton , Igor Klep , Scott McCullough

We develop an analytical approach to the study of one-dimensional free fermions subject to random projective measurements of local site occupation numbers, based on the Keldysh path-integral formalism and replica trick. In the limit of rare…

Quantum Physics · Physics 2023-12-13 Igor Poboiko , Paul Pöpperl , Igor V. Gornyi , Alexander D. Mirlin

The theory of positive kernels and associated reproducing kernel Hilbert spaces, especially in the setting of holomorphic functions, has been an important tool for the last several decades in a number of areas of complex analysis and…

Operator Algebras · Mathematics 2016-02-03 Joseph A. Ball , Gregory Marx , Victor Vinnikov

This article is devoted to the study of several algebras which are related to symmetric functions, and which admit linear bases labelled by various combinatorial objects: permutations (free quasi-symmetric functions), standard Young…

Combinatorics · Mathematics 2013-02-12 G. Duchamp , F. Hivert , J. -Y. Thibon

Consider a tensor product of free algebras over a field $k$, the so-called multipartite free algebra $A=k \langle X^{(1)}\rangle\otimes\cdots\otimes k\langle X^{(G)}\rangle$. It is well-known that $A$ is a domain, but not a fir nor even a…

Rings and Algebras · Mathematics 2020-12-07 Igor Klep , Victor Vinnikov , Jurij Volčič

We introduce a general context involving a presheaf A and a subpresheaf B of A. We show that all previously considered cases of local analysis of generalized functions (defined from duality or algebraic techniques) can be interpretated as…

Functional Analysis · Mathematics 2007-11-26 Jean-André Marti

We introduce a new type of local and microlocal asymptotic analysis in algebras of generalized functions, based on the presheaf properties of those algebras and on the properties of their elements with respect to a regularizing parameter.…

Functional Analysis · Mathematics 2009-04-18 Antoine Delcroix , Michael Oberguggenberger , Jean-André Marti

In this paper we develop a theory of free holomorphic functions on noncommutative Reinhardt domains generated by positive regular free holomorphic functions in n noncommuting variables. We show that the free biholomorphic classification of…

Operator Algebras · Mathematics 2011-11-15 Gelu Popescu
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