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We will consider completely positive maps defined on tensor products of von Neumann algebras and taking values in the algebra of bounded operators on a Hilbert space and particularly certain convex subsets of the set of such maps. We show…

Quantum Physics · Physics 2014-03-21 Erkka Haapasalo , Teiko Heinosaari , Juha-Pekka Pellonpää

We initiate and study the theory of ``real decomposable maps" between real operator systems. Formally, this is new even in the complex case, which hitherto has restricted itself to the case where the systems are complex C*-algebras. We…

Operator Algebras · Mathematics 2026-05-11 David P. Blecher , Christiaan H. Pretorius

A cross matrix $X$ can have nonzero elements located only on the main diagonal and the anti-diagonal, so that the sparsity pattern has the shape of a cross. It is shown that $X$ can be factorized into products of matrices that are at most…

Numerical Analysis · Mathematics 2025-04-02 Xiaobo Liu

To better understand the algebra $\mathcal{M}_n$ of all $n\times n$ complex matrices, we explore the class of accretive matrices. This class has received renowned attention in recent years due to its role in complementing those results…

Functional Analysis · Mathematics 2022-10-18 Hamid Reza Moradi , Shigeru Furuichi , Mohammad Sababheh

In this paper we present some factorization properties for unbounded local positive maps. We show that an unbounded local positive map $\phi $ on the minimal tensor product of the locally $C^{\ast }$-algebras $\mathcal{A}$ and $C^{\ast…

Operator Algebras · Mathematics 2022-04-19 Maria Joiţa

In factoring matrices into the product of two matrices operations are typically performed with elements restricted to matrix subspaces. Such modest structural assumptions are realistic, for example, in large scale computations. This paper…

Functional Analysis · Mathematics 2011-12-01 Marko Huhtanen

We outline a new approach to the characterization as well as to the classification of positive maps. This approach is based on the facial structures of the set of states and of the cone of positive maps. In particular, the equivalence…

Quantum Physics · Physics 2007-05-23 Wladyslaw Adam Majewski

We consider the factorization of a rectangular matrix $X $ into a positive linear combination of rank-one factors of the form $u v^\top$, where $u$ and $v$ belongs to certain sets $\mathcal{U}$ and $\mathcal{V}$, that may encode specific…

Machine Learning · Computer Science 2013-09-13 Francis Bach

Let $\mathscr{R}$ be a finite von Neumann algebra with a faithful tracial state $\tau $ and let $\Delta$ denote the associated Fuglede-Kadison determinant. In this paper, we characterize all unital bijective maps $\phi$ on the set of…

Operator Algebras · Mathematics 2018-12-24 Marcell Gaál , Soumyashant Nayak

Given an admissible map F for a homogeneous network N, it is known that the Jacobian DF(x) around a fully synchronous point x = (x0, ..., x0) is again an admissible map for N. Motivated by this, we study the spectra of linear admissible…

Dynamical Systems · Mathematics 2019-10-04 Lee DeVille , Eddie Nijholt

We show that Connes' embedding conjecture on von Neumann algebras is equivalent to the existence of certain algebraic certificates for a polynomial in noncommuting variables to satisfy the following nonnegativity condition: The trace is…

Operator Algebras · Mathematics 2011-04-19 Igor Klep , Markus Schweighofer

Existing nonnegative matrix factorization methods focus on learning global structure of the data to construct basis and coefficient matrices, which ignores the local structure that commonly exists among data. In this paper, we propose a new…

Machine Learning · Computer Science 2019-07-10 Chong Peng , Zhao Kang , Chenglizhao Chen , Qiang Cheng

Let G be a block matrix function with one diagonal block A being positive definite and the off diagonal blocks complex conjugates of each other. Conditions are obtained for G to be factorable (in particular, with zero partial indices) in…

Functional Analysis · Mathematics 2018-03-29 Ilya M. Spitkovsky , Anatoly F. Voronin

Given a Lipschitz map $f$ from a cube into a metric space, we find several equivalent conditions for $f$ to have a Lipschitz factorization through a metric tree. As an application we prove a recent conjecture of David and Schul. The…

Metric Geometry · Mathematics 2022-03-21 Behnam Esmayli , Piotr Hajłasz

We describe a simple approach to factorize non-commutative (nc) polynomials, that is, elements in free associative algebras (over a commutative field), into atoms (irreducible elements) based on (a special form of) their minimal linear…

Rings and Algebras · Mathematics 2018-08-09 Konrad Schrempf

We study a class of parametrizations of convex cones of positive semidefinite matrices with prescribed zeros. Each such cone corresponds to a graph whose non-edges determine the prescribed zeros. Each parametrization in this class is a…

Algebraic Geometry · Mathematics 2012-02-13 Mathias Drton , Josephine Yu

Positive bi-linear maps between matrix algebras play important roles to detect tri-partite entanglement by the duality between bi-linear maps and tri-tensor products. We exhibit indecomposable positive bi-linear maps between $2\times 2$…

Functional Analysis · Mathematics 2017-09-21 Seung-Hyeok Kye

Let $\Fth$ be a single vertex \textsf{k}-graph, and $\pi_\omega(\O_\theta)"$ be the von Neumann algebra induced from the GNS representation of a distinguished state $\omega$ of its $\textsf{k}$-graph C*-algebra $\O_\theta$. In this paper,…

Operator Algebras · Mathematics 2015-09-08 Dilian Yang

Parametric models in vector spaces are shown to possess an associated linear map. This linear operator leads directly to reproducing kernel Hilbert spaces and affine- / linear- representations in terms of tensor products. From the…

Numerical Analysis · Mathematics 2018-06-19 Hermann G. Matthies , Roger Ohayon

Topical maps are a nonlinear generalization of nonnegative matrices acting on the interior of the standard cone $\mathbb{R}^n_{\ge 0}$. Several analogues of irreducibility have been defined for topical maps, and all are sufficient to…

Functional Analysis · Mathematics 2025-10-15 Brian Lins