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It is shown that the *-algebra of all (closed densely defined linear) operators affiliated with a finite type I von Neumann algebra admits a unique center-valued trace, which turns out to be, in a sense, normal. It is also demonstrated that…

Operator Algebras · Mathematics 2017-05-26 Piotr Niemiec , Adam Wegert

In this paper, our primary objective is to study a possible decomposition of an approximately convex sequence. For a given $\varepsilon>0$; a sequence $\big<u_n\big>_{n=0}^{\infty}$ is said to be $\varepsilon$-convex, if for any…

General Mathematics · Mathematics 2024-06-25 Angshuman Robin Goswami

Let $A$ be a unital separable simple $C^*$-algebra with tracial rank zero and let $x, \, y\in A$ be two normal elements. We show that $x$ is in the closure of the convex full of the unitary obit of $y$ if and only if there exists a sequence…

Operator Algebras · Mathematics 2018-05-17 Shanwen Hu , Huaxin Lin

We first prove that in a sigma-finite von Neumann factor M, a positive element $a$ with properly infinite range projection R_a is a linear combination of projections with positive coefficients if and only if the essential norm ||a||_e with…

Operator Algebras · Mathematics 2010-07-28 Herbert Halpern , Victor Kaftal , Ping Wong Ng , Shuang Zhang

A general method for proving continuity of the von Neumann entropy on subsets of positive trace-class operators is considered. This makes it possible to re-derive the known conditions for continuity of the entropy in more general forms and…

Mathematical Physics · Physics 2015-05-13 M. E. Shirokov

We prove that there exists an absolute constant $\alpha >1$ with the following property: if $K$ is a convex body in ${\mathbb R}^n$ whose center of mass is at the origin, then a random subset $X\subset K$ of cardinality ${\rm…

Metric Geometry · Mathematics 2015-12-16 Silouanos Brazitikos , Giorgos Chasapis , Labrini Hioni

Suppose that $\mathcal{X}$ is a sequentially complete Hausdorff locally convex space over a scalar field $\mathbb{K}$, $V$ is a bounded subset of $\mathcal{X}$, $(a_n)_{n\ge 0}$ is a sequence in $\mathbb{K}\setminus\{0\}$ with the property\…

Functional Analysis · Mathematics 2012-03-22 Mohammad Sal Moslehian , Dorian Popa

A sequence $\Big(u_n\Big)_{n=0}^{\infty}$ is said to be convex if it satisfies the following inequality $$ 2u_n\leq u_{n-1}+u_{n+1}\qquad \mbox{for all}\qquad n\in\mathbb{N}. $$ We present several characterizations of convex sequences and…

General Mathematics · Mathematics 2025-05-30 Angshuman Robin Goswami

In this article, we address the following question: Is it true that the spatial numerical range (SNR) $V_A(a)$ of an element $a$ in a normed algebra $(A, \|\cdot\|)$ is always convex? If the normed algebra is unital, then it is convex…

Functional Analysis · Mathematics 2023-06-29 H. V. Dedania , A. B. Patel

In the present article, it is proved that every nuclear operator in a locally convex space E has a well-defined trace if E possesses the approximation property. However, even if a space possesses the approximation property this still does…

Functional Analysis · Mathematics 2016-11-25 Grigory L. Litvinov

We investigate criteria for von-Neumann finiteness and reversibility in some classes of non-associative algebras. We show that all finite-dimensional alternative algebras, as well as all algebras obtained from the real numbers via the…

Rings and Algebras · Mathematics 2020-09-02 Erik Darpö , Patrik Nystedt

We present a novel approach to the representation theory of finite dimensional algebras motivated by the emerging theory of graph limits. We introduce the rank spectrum of a finite dimensional algebra $R$ over a finite field. The elements…

Representation Theory · Mathematics 2016-03-15 Gabor Elek

Let L_1 be the predual of a von Neumann algebra with a finite faithful normal trace. We show that a bounded sequence in L_1 converges to 0 in measure if and only if each of its subsequences admits another subsequence which converges to 0 in…

Functional Analysis · Mathematics 2007-05-23 Hermann Pfitzner

We show that any countably generated von Neumann algebra with specified normal faithful state can arise as the tail algebra of a quantum exchangeable sequence of noncommutative random variables. We also characterize the cases when the state…

Operator Algebras · Mathematics 2012-12-13 Kenneth J. Dykema , Claus Köstler

Suppose F is a finite set of selfadjoint elements in a tracial von Neumann algebra M. For $\alpha >0$, F is $\alpha$-bounded if the free packing $\alpha$-entropy of F is bounded from above. We say that M is strongly 1-bounded if M has a…

Operator Algebras · Mathematics 2007-05-23 Kenley Jung

We introduce the relative Haagerup approximation property for a unital, expected inclusion of arbitrary von Neumann algebras and show that if the smaller algebra is finite then the notion only depends on the inclusion itself, and not on the…

Operator Algebras · Mathematics 2023-03-29 Martijn Caspers , Mario Klisse , Adam Skalski , Gerrit Vos , Mateusz Wasilewski

Suppose that c is an operator on a Hilbert Space H such that the von Neumann algebra N generated by c is finite. Suppose that tau is a faithful normal tracial state on N. Let B denote the spectal scale of c with respect to tau. We show that…

Operator Algebras · Mathematics 2007-05-23 Charles A. Akemann , Joel Anderson

We show that any finite dimensional von Neumann algebra admits an orthonormal unitary basis with respect to its standard trace. We also show that a finite dimensional von Neumann subalgebra of $M_n(\mathbb{C})$ admits an orthonormal unitary…

Operator Algebras · Mathematics 2022-11-22 Jason Crann , David W. Kribs , Rajesh Pereira

Given a von Neumann algebra $M$ with a faithful normal finite trace, we introduce the so called finite tracial algebra $M_f$ as the intersection of $L_p$-spaces $L_p(M, \mu)$ over all $p \geq 1$ and over all faithful normal finite traces…

Operator Algebras · Mathematics 2009-08-11 Sh. A. Ayupov , R. Z. Abdullaev , K. K. Kudaybergenov

We study the space of traces associated with arbitrary full free products of unital, separable $C^*$-algebras. We show that, unless certain basic obstructions (which we fully characterize) occur, the space of traces always results in the…

Operator Algebras · Mathematics 2024-12-19 Adrian Ioana , Pieter Spaas , Itamar Vigdorovich
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