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Let $A$ be a matrix with nonnegative real entries. A nonnegative factorization of size $k$ is a representation of $A$ as a sum of $k$ nonnegative rank-one matrices. The space of all such factorizations is a bounded semialgebraic set, and we…

Combinatorics · Mathematics 2018-04-06 Yaroslav Shitov

McMullen proved the moduli space of complex rational maps can be parametrized by the spectrum of all periodic-point multipliers up to a finite amount of data, with the well-understood exception of Latt\`{e}s maps. We generalize his method…

Number Theory · Mathematics 2014-10-10 Alon Levy

We prove that for Noetherian, smooth, separated, integral, finite type schemes $X$ and $Y$ over an excellent Dedekind domain $R$, that are properly birational over $R$, we have $R^if_{*}\mathcal{O}_X \cong R^ig_{*} \mathcal{O}_Y$ and $R^i…

Algebraic Geometry · Mathematics 2026-02-17 Grétar Amazeen

One proves a far-reaching upper bound for the degree of a generically finite rational map between projective varieties over a base field of arbitrary characteristic. The bound is expressed as a product of certain degrees that appear…

Commutative Algebra · Mathematics 2021-01-29 M. Chardin , S. H. Hassanzadeh , A. Simis

Finite rational $\cw$ algebras are very natural structures appearing in coset constructions when a Kac-Moody subalgebra is factored out. In this letter we address the problem of relating these algebras to integrable hierarchies of…

High Energy Physics - Theory · Physics 2009-10-22 Francesco Toppan

Let $\mathcal{B} (X)$ be the algebra of all bounded linear operators on an infinite-dimensional complex Banach space $X$. In this note, we show that a lemma used in the proof of the main result of [ Taghavi and Hosseinzadeh, linear and…

Functional Analysis · Mathematics 2024-12-03 S. Elouazzani , M. Elhodaibi , S. Saber

Let $M_n(\mathbb{F})$ denote the algebra of $n \times n$ matrices over an algebraically closed field $\mathbb{F}$ of characteristic different from $2$. For $n \ge 2$, we classify all maps $\phi : M_n(\mathbb{F}) \to M_n(\mathbb{F})$…

Rings and Algebras · Mathematics 2025-12-16 Ilja Gogić , Mateo Tomašević

Let $M_n$ denote the algebra of $n \times n$ complex matrices and let $\mathcal{A}\subseteq M_n$ be an arbitrary structural matrix algebra, i.e. a subalgebra of $M_n$ that contains all diagonal matrices. We consider injective maps $\phi :…

Rings and Algebras · Mathematics 2025-11-26 Ilja Gogić , Mateo Tomašević

A non-zero constant Jacobian polynomial maps $F=(P,Q)$ of $\mathbb{C}^2$ is invertible if $P$ and $Q$ are rational polynomials.

Algebraic Geometry · Mathematics 2017-09-13 Nguyen Van Chau

The purpose of this short note is to clarify and present a general version of an interesting observation by Piani and Mora (Physic. Rev. A 75, 012305 (2007)), linking complete positivity of linear maps on matrix algebras to decomposability…

Quantum Physics · Physics 2019-12-09 B. V. Rajarma Bhat , Hiroyuki Osaka

A problem of completing a linear map on C*-algebras to a completely positive map is analyzed. It is shown that whenever such a completion is feasible there exists a unique minimal completion. This theorem is used to show that under some…

Operator Algebras · Mathematics 2024-05-28 B. V. Rajarama Bhat , Arghya Chongdar

In a graph whose vertices are assigned integer ranks, a path is well-ranked if the endpoints have distinct ranks or some interior point has a higher rank than the endpoints. A ranking is an assignment of ranks such that all nontrivial paths…

Combinatorics · Mathematics 2016-07-26 Jordan Almeter , Samet Demircan , Andrew Kallmeyer , Kevin G. Milans , Robert Winslow

We characterise absolutely dilatable completely positive maps on the space of all bounded operators on a Hilbert space that are also bimodular over a given von Neumann algebra as rotations by a suitable unitary on a larger Hilbert space…

Operator Algebras · Mathematics 2025-04-25 Alexandros Chatzinikolaou , Ivan G. Todorov , Lyudmila Turowska

Let $\iota : \C^2 \hookrightarrow S$ be a compactification of the two dimensional complex space $\C^2$. By making use of Nevanlinna theoretic methods and the classification of compact complex surfaces K. Kodaira proved in 1971 (\cite{ko71})…

Complex Variables · Mathematics 2011-03-31 Junjiro Noguchi , Jörg Winkelmann

We describe $\omega$-limit sets of completely positive (CP) maps over finite-dimensional spaces. In such sets and in its corresponding convex hulls, CP maps present isometric behavior and the states contained in it commute with each other.…

Mathematical Physics · Physics 2016-12-20 Carlos F. Lardizabal

The dual of a matrix ordered space has a natural matrix ordering that makes the dual space matrix ordered as well. The purpose of these notes is to give a condition that describes when the linear map taking a basis of the n by n matrices to…

Quantum Physics · Physics 2015-06-12 Vern I. Paulsen , Fred Shultz

An open question is whether the map $\widetilde{K_0 }\mathbb{Z} G \rightarrow \widetilde{K_0 }\mathbb{Q} G$ in reduced $K$-theory from the integral to the rational group ring is trivial for any group $G$. We will show that this is false,…

K-Theory and Homology · Mathematics 2025-10-20 Georg Lehner

Let $R=K[[x_1,...,x_s]]$ be the ring of formal power series with maximal ideal $\mathfrak{m}$ over a field $K$ of arbitrary characteristic. On the ring $M_{m,n}$ of $m\times n$ matrices $A$ with entries in $R$ we consider several…

Algebraic Geometry · Mathematics 2016-09-19 Gert-Martin Greuel , Thuy Huong Pham

We study the geometry of the image of the nonnegative orthant under the power-sum map and the elementary symmetric polynomials map. After analyzing the image in finitely many variables, we concentrate on the limit as the number of variables…

Algebraic Geometry · Mathematics 2024-12-06 Jose Acevedo , Grigoriy Blekherman , Sebastian Debus , Cordian Riener

The concept of the {\em half density matrix} is proposed. It unifies the quantum states which are described by density matrices and physical processes which are described by completely positive maps. With the help of the half-density-matrix…

Quantum Physics · Physics 2009-11-06 Sixia Yu