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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

We study the question of whether or not contractive representations of logmodular algebras are completely contractive. We prove that a 2-contractive representation of a logmodular algebra extends to a positive map on the enveloping…

Operator Algebras · Mathematics 2010-03-24 Vern I. Paulsen , Mrinal Raghupathi

The new notion of operator/matrix $k$-tone functions is introduced, which is a higher order extension of operator/matrix monotone and convex functions. Differential properties of matrix $k$-tone functions are shown. Characterizations,…

Functional Analysis · Mathematics 2014-05-19 Uwe Franz , Fumio Hiai , Éric Ricard

In this paper we investigate algebraic function fields in positive characteristic mainly obtained as double Artin-Schreier extensions of rational function fields with a plane model. The goal is to extend to such extensions large…

Algebraic Geometry · Mathematics 2026-02-17 Herivelto Borges , Jonathan Niemann , Giovanni Zini

We give a short proof for the Hartogs's extension theorem on (n-1)-complete complex spaces.

Complex Variables · Mathematics 2008-11-17 Mihnea Colţoiu

We continue our study of operator algebras with contractive approximate identities (cais). In earlier papers we have introduced and studied a new notion of positivity in operator algebras, with an eye to extending certain $C^*$-algebraic…

Operator Algebras · Mathematics 2013-09-17 David P. Blecher , Charles John Read

We study the properties of shifted vertex operator algebras, which are vertex algebras derived from a given theory by shifting the conformal vector. In this way, we are able to exhibit large numbers of vertex operator algebras which are…

Quantum Algebra · Mathematics 2007-05-23 Chongying Dong , Geoffrey Mason

We present some operator inequalities for positive linear maps that generalize and improve the derived results in some recent years. For instant, if $A$ and $B$ are positive operators and $m,m^{'},M,M^{'}$ are positive real numbers…

Functional Analysis · Mathematics 2018-01-09 Leila Nasiri , Mojtaba Bakherad

We investigate linear maps between matrix algebras that remain positive under tensor powers, i.e., under tensoring with $n$ copies of themselves. Completely positive and completely co-positive maps are trivial examples of this kind. We show…

Quantum Physics · Physics 2015-12-22 Alexander Müller-Hermes , David Reeb , Michael M. Wolf

We prove some extension results for holomorphic mappings with values in complex Hilbert manifolds

Complex Variables · Mathematics 2019-10-02 M. Anakkar , A. Zagorodnyuk

We link the study of positive quantum maps, block positive operators, and entanglement witnesses with problems related to multivariate polynomials. For instance, we show how indecomposable block positive operators relate to biquadratic…

Mathematical Physics · Physics 2009-11-28 Lukasz Skowronek , Karol Zyczkowski

We show that an operator valued $\alpha$-completely positive map on a group G is given by a unitary representation of G on a Krein space which satisfies some condition. Moreover, two unitary equivalent such unitary representations define…

Operator Algebras · Mathematics 2013-08-08 Maria Joiţa

We introduce and study $\alpha$-embedded sets and apply them to generalize the Kuratowski Extension Theorem.

General Topology · Mathematics 2014-07-24 Olena Karlova

Permutation rational functions over finite fields have attracted high interest in recent years. However, only a few of them have been exhibited. This article studies a class of permutation rational functions constructed using trace maps on…

Number Theory · Mathematics 2024-01-01 Ruikai Chen , Sihem Mesnager

We give a direct non-abstract proof of the Spectral Mapping Theorem for the Helffer-Sj\"ostrand functional calculus for linear operators on Banach spaces with real spectra and consequently give a new non-abstract direct proof for the…

Spectral Theory · Mathematics 2012-07-16 Narinder S Claire

Algorithmic methods for the explicit inversion of the indefinite double covering maps are proposed. These are based on either the Givens decomposition or the polar decomposition of the given matrix in the proper, indefinite orthogonal group…

Mathematical Physics · Physics 2020-03-24 Francis Adjei , Mieczyslaw Dabkowski , Samreen Khan , Viswanath Ramakrishna

Given a bounded linear operator $T$ on separable Hilbert space, we develop an approach allowing one to construct a matrix representation for $T$ having certain specified algebraic or asymptotic structure. We obtain matrix representations…

Functional Analysis · Mathematics 2020-10-20 Vladimir Müller , Yuri Tomilov

We generalize Feigin and Miwa's construction of extended vertex operator (super)algebras $A_{k}(sl(2))$ for other types of simple Lie algebras. For all the constructed extended vertex operator (super)algebras, irreducible modules are…

Quantum Algebra · Mathematics 2009-10-31 Haisheng Li

On the set of mappings of the given set, we define the product of mappings. If A is associative algebra, then we consider the set of matrices, whose elements are linear mappings of algebra A. In algebra of matrices of linear mappings we…

General Mathematics · Mathematics 2010-01-28 Aleks Kleyn

We say a completely positive contractive map between two C*-algebras has order zero, if it sends orthogonal elements to orthogonal elements. We prove a structure theorem for such maps. As a consequence, order zero maps are in one-to-one…

Operator Algebras · Mathematics 2009-03-20 Wilhelm Winter , Joachim Zacharias