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We give a characterization of the ''uniform closure'' of the dual of a $C^{*}$-algebra. Some applications in harmonic analysis are given.

Operator Algebras · Mathematics 2007-05-23 Massoud Amini

We prolonge the list of C*-algebras for which all extensions by any stable separable C*-algebra are semi-invertible. In particular, we handle certain amalgamations, both of C*-algebras and of groups. Concerning groups we consider both…

Operator Algebras · Mathematics 2010-05-13 Vladimir Manuilov , Klaus Thomsen

Morphisms and representations of a class of Banach C*-modules, called CQ*algebras, are considered. Together with a general method for constructing CQ*-algebras, two different ways of extending the GNS-representation are presented.

Mathematical Physics · Physics 2009-04-07 F. Bagarello , C. Trapani

A complete classifications, up to isomorphism, of two-dimensional associative and diassociative algebras over any basic field are given.

Rings and Algebras · Mathematics 2023-07-20 I. S. Rakhimov

We obtain necessary and sufficient conditions for a matrix $A$ to be Birkhoff-James orthogonal to another matrix $B$ in the Ky Fan $k$-norms. A characterization for $A$ to be Birkhoff-James orthogonal to any subspace $\mathscr W$ of…

Functional Analysis · Mathematics 2016-12-26 Priyanka Grover

We classify the category of finite-dimensional real division composition algebras having a non-abelian Lie algebra of derivations. Our complete and explicit classification is largely achieved by introducing the concept of a…

Rings and Algebras · Mathematics 2015-09-18 Seidon Alsaody

We classify the $4$-dimensional nilpotent bicommutative algebras over $\mathbb C$ from both algebraic and geometric approaches.

Rings and Algebras · Mathematics 2020-04-03 Ivan Kaygorodov , María Pilar Paez Guillán , Vasily Voronin

Using adjoint representation of Lie superalgebras, we obtain the matrix form of super-Jacobi and mixed super-Jacobi identities of Lie superbialgebras. By direct calculations of these identities, and use of automorphism supergroups of two…

Mathematical Physics · Physics 2015-05-13 A. Eghbali , A. Rezaei-Aghdam , F. Heidarpour

We investigate the ideal structures of the C^*-algebras arising from topological graphs. We give the complete description of ideals of such C^*-algebras which are invariant under the so-called gauge action, and give the condition on…

Operator Algebras · Mathematics 2007-05-23 Takeshi Katsura

We introduce the notion of almost finite dimensionality of algebras and study its connection with the classical finiteness conditions.

Rings and Algebras · Mathematics 2007-05-23 Gábor Elek

The first aim of this paper is to introduce and study symmetric (Bi)Hom-Leibniz algebras, which are left and right Leibniz algebras. We discuss $\alpha^k\beta^l$-generalized derivations, $\alpha^k\beta^l$ -quasi-derivations and…

Rings and Algebras · Mathematics 2019-08-23 Saadaoui Nejib

We write arbitrary separable nuclear C*-algebras as limits of inductive systems of finite-dimensional C*-algebras with completely positive connecting maps. The characteristic feature of such CPC*-systems is that the maps become more and…

Operator Algebras · Mathematics 2024-10-10 Kristin Courtney , Wilhelm Winter

We show that certain extensions of classifiable C*-algebra are strongly classified by the associated six-term exact sequence in K-theory together with the positive cone of K_{0}-groups of the ideal and quotient. We apply our result to give…

Operator Algebras · Mathematics 2013-02-01 Soren Eilers , Gunnar Restorff , Efren Ruiz

The Lie algebra of planar vector fields with coefficients from the field of rational functions over an algebraically closed field of characteristic zero is considered. We find all finite-dimensional Lie algebras that can be realized as…

Rings and Algebras · Mathematics 2013-01-10 Ievgen Makedonskyi , Anatoliy Petravchuk

We present a common framework to study varieties in great generality from a categorical point of view. The main application of this study is in the setting of algebraic categories, where we introduce Birkhoff varieties which are essentially…

Category Theory · Mathematics 2023-10-12 Jose Avila

The work is devoted to the variety of $2$-dimensional algebras over an algebraically closed field. Firstly, we classify such algebras modulo isomorphism. Then we describe the degenerations and the closures of principal algebra series in the…

Rings and Algebras · Mathematics 2020-04-03 Ivan Kaygorodov , Yury Volkov

We give a sufficient condition for a $^*$-algebra with a specified basis to have an enveloping $C^*$-algebra. Particularizing to the setting of a Hecke algebra $\h(G,\gm)$, we show that under a suitable assumption not only we can assure…

Operator Algebras · Mathematics 2012-11-30 Rui Palma

Let $\Gamma$ be a discrete group. To every ideal in $\ell^{\infty}(\G)$ we associate a C$^*$-algebra completion of the group ring that encapsulates the unitary representations with matrix coefficients belonging to the ideal. The general…

Operator Algebras · Mathematics 2014-02-26 Nathanial P. Brown , Erik Guentner

We obtained a "decomposition scheme" of C*-algebras. We show that the classes of discrete C*-algebras (as defined by Peligard and Zsido), type II C*-algebras and type III C*-algebras (both defined by Cuntz and Pedersen) form a good…

Operator Algebras · Mathematics 2016-09-29 Chi-Keung Ng , Ngai-Ching Wong

Let $\mathbb{F}_{p^k}$ be a finite field of odd characteristic $p$. In this paper we give a classification, up to isomorphism, of the associative commutative $\mathbb{F}_{p^k}$-algebras, starting from the connection with their bi-brace…

Group Theory · Mathematics 2025-07-09 Riccardo Aragona , Giuseppe Nozzi
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