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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 prove that the coarse assembly maps for proper metric spaces which are non-positively curved in the sense of Busemann are isomorphisms, where we do not assume that the spaces are with bounded coarse geometry. Also it is shown that we can…

K-Theory and Homology · Mathematics 2018-10-23 Tomohiro Fukaya , Shin-ichi Oguni

We provide a concise proof of existence for nonlinear operator equations in separable Banach spaces. Notably, the operator is not assumed to be monotone. Instead, our main hypotheses consist of a continuity assumption and a generalized…

Analysis of PDEs · Mathematics 2025-03-21 Roland Becker , Malte Braack

For every strong coarse homology theory we construct a coarse assembly map as a natural transformation between coarse homology theories. We provide various conditions implying that this assembly map is an equivalence. These results…

K-Theory and Homology · Mathematics 2020-08-26 Ulrich Bunke , Alexander Engel

In this paper we consider power means of positive Hilbert space operators both in the conventional and in the Kubo-Ando senses. We describe the corresponding isomorphisms (bijective transformations respecting those means as binary…

Functional Analysis · Mathematics 2019-09-26 Lajos Molnár

We provide a characterization of when a coarse equivalence between coarse disjoint unions of expander graphs is close to a bijective coarse equivalence. We use this to show that if the uniform Roe algebras of coarse disjoint unions of…

Metric Geometry · Mathematics 2023-07-24 Florent Baudier , Bruno de Mendonça Braga , Ilijas Farah , Alessandro Vignati , Rufus Willett

This article contains a characterization of operator systems $\cS$ with the property that every positive map $\phi:\cS \rightarrow M_n$ is decomposable, as well as an alternate and a more direct proof of a characterization of decomposable…

Operator Algebras · Mathematics 2020-06-23 Sriram Balasubramanian

In this paper we define the coarse (co)homology of the complement of a subspace in a metric space, generalizing the coarse (co)homology of Roe. We give a model space which encodes coarse geometric structure of the complement. We also…

Geometric Topology · Mathematics 2023-08-29 Arka Banerjee , Boris Okun

A necessary and sufficient condition for an operator space to support a multiplication making it completely isometric and isomorphic to a unital operator algebra is proved. The condition involves only the holomorphic structure of the Banach…

Operator Algebras · Mathematics 2015-12-11 Matthew Neal , Bernard Russo

A proof using the theory of completely positive maps is given to the fact that if $A \in M_2$, or $A \in M_3$ has a reducing eigenvalue, then every bounded linear operator $B$ with $W(B) \subseteq W(A)$ has a dilation of the form $I \otimes…

Functional Analysis · Mathematics 2019-02-07 Chi-Kwong Li , Yiu-Tung Poon

We give a definition of coarse quotient mapping and show that several results for uniform quotient mapping also hold in the coarse setting. In particular, we prove that any Banach space that is a coarse quotient of $L_p\equiv L_p[0,1]$,…

Functional Analysis · Mathematics 2014-03-11 Sheng Zhang

Generalizing a recent result on lineability of sets of non-injective linear operators, we prove, for quite general linear spaces $A$ of maps from an arbitraty set to a sequence space, that, for every $0 \neq f \in A$, the subset of $A$ of…

Functional Analysis · Mathematics 2024-04-16 Mikaela Aires , Geraldo Botelho

In this paper, we study {\it operator spaces\/} in the sense of the theory developed recently by Blecher-Paulsen [BP] and Effros-Ruan [ER1]. By an operator space, we mean a closed subspace $E\subset B(H)$, with $H$ Hilbert. We will be…

Functional Analysis · Mathematics 2016-09-06 Gilles Pisier

We continue our study of the mapping ideal of operator $p$-compact maps, previously introduced by the authors. Our approach embraces a more geometric perspective, delving into the interplay between operator $p$-compact mappings and matrix…

Functional Analysis · Mathematics 2025-06-09 Javier Alejandro Chávez-Domínguez , Verónica Dimant , Daniel Galicer

We show that if an infinite-dimensional Banach space X has a symmetric basis then there exists a bounded, linear operator R : X --> X such that the set A = {x in X : ||R^n(x)|| --> infinity} is non-empty and nowhere dense in X. Moreover, if…

Functional Analysis · Mathematics 2022-06-14 Petr Hajek , Richard J. Smith

In this article, we introduce the notion of a functor on coarse spaces being coarsely excisive- a coarse analogue of the notion of a functor on topological spaces being excisive. Further, taking cones, a coarsely excisive functor yields a…

Algebraic Topology · Mathematics 2014-10-01 Paul D. Mitchener

We prove a factorization of completely bounded maps from a $C^*$-algebra $A$ (or an exact operator space $E\subset A$) to $\ell_2$ equipped with the operator space structure of $(C,R)_\theta$ ($0<\theta<1$) obtained by complex interpolation…

Operator Algebras · Mathematics 2007-05-23 Gilles Pisier

We prove several versions of Grothendieck's Theorem for completely bounded linear maps $T\colon E \to F^*$, when E and F are operator spaces. We prove that if E,F are $C^*$-algebras, of which at least one is exact, then every completely…

Operator Algebras · Mathematics 2015-06-26 Gilles Pisier , Dimitri Shlyakhtenko

We show that there is an operator space notion of Lipschitz embeddability between operator spaces which is strictly weaker than its linear counterpart but which is still strong enough to impose linear restrictions on operator space…

Operator Algebras · Mathematics 2022-11-28 Bruno de Mendonça Braga , Javier Alejandro Chávez-Domínguez , Thomas Sinclair

In this paper we study sufficient conditions for an operator to have an almost-invariant half-space. As a consequence, we show that if $X$ is an infinite-dimensional complex Banach space then every operator $T\in\mathcal{L}(X)$ admits an…

Functional Analysis · Mathematics 2015-10-06 Gleb Sirotkin , Ben Wallis