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We continue our study of group algebras acting on $L^p$-spaces, particularly of algebras of $p$-pseudofunctions of locally compact groups. We focus on the functoriality properties of these objects. We show that $p$-pseudofunctions are…

Functional Analysis · Mathematics 2014-08-27 Eusebio Gardella , Hannes Thiel

We prove that the Cuntz-Pimsner algebra O(E) of a vector bundle E over a compact metrizable space X is determined up to an isomorphism of C(X)-algebras by the ideal (1-[E])K(X) of the K-theory ring K(X). Moreover, if E and F are vector…

Operator Algebras · Mathematics 2010-04-27 Marius Dadarlat

In the framework of idempotent mathematics, analogs of the classical kernel theorems of L. Schwartz and A. Grothendieck are studied. Idempotent versions of nuclear spaces (in the sense of A. Grothendieck) are discussed. The so-called…

Functional Analysis · Mathematics 2007-05-23 G. L. Litvinov , G. B. Shpiz

Let k be a commutative ring. We find and characterize a new family of twisted planes (i. e. associative unitary k-algebra structures on the k-module k[X,Y], having k[X] and and k[Y] as subalgebras).Similar results are obtained for the…

Rings and Algebras · Mathematics 2007-12-27 Jorge A. Guccione , Juan J. Guccione , Christian Valqui

We study the structure of an idempotent matrix $F$ over a commutative ring. We make explicit the fundamental system of orthogonal idempotents, hidden in this matrix, for each of which the matrix has a well-defined rank. Similarly we find a…

Commutative Algebra · Mathematics 2023-08-21 Henri Lombardi

In this article we describe the $G_{comp}\times G_{comp}$-equivariant topological $K$-ring of a {\em cellular} toroidal embedding $\mathbb{X}$ of a complex connected reductive algebraic group $G$. In particular, our results extend the…

Algebraic Geometry · Mathematics 2025-06-11 Alexis Tchoudjem , V. Uma

We prove that the tangent space to the $(n+1)$-th Milnor $K$-group of a ring $R$ is isomorphic to group of $n$-th absolute K\"ahler differentials of $R$ when the ring $R$ contains $\frac{1}{2}$ and has sufficiently many invertible elements.…

Algebraic Geometry · Mathematics 2015-09-29 S. O. Gorchinskiy , D. V. Osipov

For every multivariable polynomial $p$, with $p(0)=1$, we construct a determinantal representation $$p=\det (I - K Z),$$ where $Z$ is a diagonal matrix with coordinate variables on the diagonal and $K$ is a complex square matrix. Such a…

Functional Analysis · Mathematics 2012-08-14 Anatolii Grinshpan , Dmitry S. Kaliuzhnyi-Verbovetskyi , Hugo J. Woerdeman

We show that for a multivariable polynomial $p(z)=p(z_1, \ldots , z_d)$ with a determinantal representation $$ p(z) = p(0) \det (I_n- K (\oplus_{j=1}^d z_j I_{n_j}))$$ the matrix $K$ is structurally similar to a strictly $J$-contractive…

Functional Analysis · Mathematics 2024-11-11 Gilbert J. Groenewald , Sanne ter Horst , Hugo J. Woerdeman

Given a nilpotent Lie group $N$, a compact subgroup $K$ of automorphisms of $N$ and an irreducible unitary representation $(\tau,W_\tau)$ of $K$, we study conditions on $\tau$ for the commutativity of the algebra of…

Representation Theory · Mathematics 2020-02-18 Rocío Díaz Martín , Linda Saal

Let $R$ be a semiartinian (von Neumann) regular ring with primitive factors artinian. The dimension sequence $\mathcal D _R$ is an invariant that captures the various skew-fields and dimensions occurring in the layers of the socle sequence…

Rings and Algebras · Mathematics 2025-04-24 Kateřina Fuková , Jan Trlifaj

We describe the norm-closures of the set $\mathfrak{C}_{\mathfrak{E}}$ of commutators of idempotent operators and the set $\mathfrak{E} - \mathfrak{E}$ of differences of idempotent operators acting on a finite-dimensional complex Hilbert…

Functional Analysis · Mathematics 2022-05-19 Laurent W. Marcoux , Heydar Radjavi , Yuanhang Zhang

We investigate correspondence functors, namely the functors from the category of finite sets and correspondences to the category of $k$-modules, where $k$ is a commutative ring.They have various specific properties which do not hold for…

Representation Theory · Mathematics 2019-03-19 Serge Bouc , Jacques Thévenaz

This article is the first of two where we investigate to what extent homotopy invariant, excisive and matrix stable homology theories help one distinguish between the Leavitt path algebras $L(E)$ and $L(F)$ of graphs $E$ and $F$ over a…

K-Theory and Homology · Mathematics 2018-08-07 Guillermo Cortiñas , Diego Montero

Let $\mathcal{P}$ be the class of rings for which every indecomposable right module is pure-projective or pure-injective. When $R$ is a Noetherian local commutative ring of maximal ideal $P$, it is proven that $R\in\mathcal{P}$ if and only…

Rings and Algebras · Mathematics 2025-07-08 François Couchot

Let $R$ be a ring and $P$ a prime ideal of $R.$ In this paper, we establish some commutativity criteria for the factor ring $R/P$ in terms of derivations of $R$ satisfying some algebraic identities involving a new kind of involution in…

Rings and Algebras · Mathematics 2024-06-13 Karim Bouchannafa , Lahcen Oukhtite , Mohammed Zerra

Let $R$ be a commutative $k-$algebra over a field $k$. Assume $R$ is a noetherian, infinite, integral domain. The group of $k-$automorphisms of $R$,i.e.$Aut_k(R)$ acts in a natural way on $(R-k)$.In the first part of this article, we study…

Commutative Algebra · Mathematics 2021-02-11 Pramod K. Sharma

Let $g$ be a semisimple Lie algebra over $\mathbb C$ and $k$ be a reductive in $g$ subalgebra. We say that a simple $g$-module $M$ is a $(g; k)$-module if as a $k$-module $M$ is a direct sum of finite-dimensional $k$-modules. We say that a…

Representation Theory · Mathematics 2016-11-25 Alexey Petukhov

We consider the K-theory of the Hilbert scheme of points in the complex plane, which under McKay correspondence is isomorphic to the space of symmetric functions $\Lambda^n$. We prove a formula conjectured by Boissi\`ere for the…

Algebraic Geometry · Mathematics 2026-05-06 Jakub Koncki , Magdalena Zielenkiewicz

In this paper, we build on the work from our previous paper (arXiv:2002.01556) to show that periodic rational $G$-equivariant topological $K$-theory has a unique genuine-commutative ring structure for $G$ a finite abelian group. This means…

Algebraic Topology · Mathematics 2021-04-05 Anna Marie Bohmann , Christy Hazel , Jocelyne Ishak , Magdalena Kędziorek , Clover May