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Spielberg's construction of C*-algebras from left cancellative small categories is a common generalization for most C*-algebras one would consider to come from ``combinatorial data,'' including graph and $k$-graph C*-algebras, Li's…

Operator Algebras · Mathematics 2026-05-14 Charles Starling

A general notion of a quasi-finite algebra is introduced as an algebra graded by the set of all integers equipped with topologies on the homogeneous subspaces satisfying certain properties. An analogue of the regular bimodule is introduced…

Quantum Algebra · Mathematics 2007-05-23 Atsushi Matsuo , Kiyokazu Nagatomo , Akihiro Tsuchiya

We characterise the positive cone of a real C*-algebra geometrically. Given an open cone $\Omega$ in a real Banach space $V$, with closure $\overline \Omega$, we show that $\Omega$ is the interior of the positive cone of a unital real…

Operator Algebras · Mathematics 2024-03-20 Cho-Ho Chu

We show that a normal coaction of a discrete group on an operator algebra extends to a normal coaction on the C*-envelope. This resolves an open problem attempted by several experts in the area, and provides a more direct proof of a…

Operator Algebras · Mathematics 2026-04-06 Kevin Aguyar Brix , Chris Bruce , Adam Dor-On

Suppose that H is a complex Hilbert space and that B(H) denotes the bounded linear operators on H. We show that every abelian, amenable operator algebra is similar to a C*-algebra. We do this by showing that if A is an abelian subalgebra of…

Operator Algebras · Mathematics 2016-09-07 Laurent W. Marcoux , Alexey I. Popov

Recently Blecher and Kashyap have generalized the notion of W* modules over von Neumann algebras to the setting where the operator algebras are \sigma- weakly closed algebras of operators on a Hilbert space. They call these modules weak*…

Operator Algebras · Mathematics 2012-01-04 G. K. Eleftherakis

We show that every ring isomorphism between the algebras of locally measurable operators for type II$_\infty$ von Neumann algebras is similar to a real $^*$-isomorphism. This together with previous results by the author and…

Operator Algebras · Mathematics 2023-05-23 Michiya Mori

Let $R$ be a rational function of degree at least two, let $J_R$ be the Julia set of $R$ and let $\mu^L$ be the Lyubich measure of $R$. We study the C$^*$-algebra $\mathcal{MC}_R$ generated by all multiplication operators by continuous…

Operator Algebras · Mathematics 2015-02-10 Hiroyasu Hamada

We study crossed products of arbitrary operator algebras by locally compact groups of completely isometric automorphisms. We develop an abstract theory that allows for generalizations of many of the fundamental results from the selfadjoint…

Operator Algebras · Mathematics 2018-11-21 Elias Katsoulis , Christopher Ramsey

We present some foundations for a theory of real operator algebras and real Jordan operator algebras, and the various morphisms between these. A common theme is the ingredient of real positivity from papers of the first author with Read,…

Operator Algebras · Mathematics 2021-07-30 David P. Blecher , Worawit Tepsan

It is shown that each linear operator on a separable Hilbert space which generates a finite type I von Neumann algebra has, up to unitary equivalence, a unique representation as a direct integral of inflations of mutually unitary…

Functional Analysis · Mathematics 2017-05-26 Piotr Niemiec

In this paper we discuss some physical applications of topological *-algebras of unbounded operators. Our first example is a simple system of free bosons. Then we analyze different models which are related to this one. We also discuss the…

Operator Algebras · Mathematics 2009-10-31 F. Bagarello

We give a description of the essential spectrum of a large class of operators on metric measure spaces in terms of their localizations at infinity. These operators are analogues of the elliptic operators on Euclidean spaces and our main…

Mathematical Physics · Physics 2015-03-13 Vladimir Georgescu

Corresponding to any $(m-1)$-tuple of semi-spectral measures on the unit circle, a weighted Dirichlet-type space is introduced and studied. We prove that the operator of multiplication by the coordinate function on these weighted…

Functional Analysis · Mathematics 2022-07-07 S. Ghara , R. Gupta , Md. R. Reza

We show that every operator system (and hence every unital operator algebra) has sufficiently many boundary representations to generate the C*-envelope.

Operator Algebras · Mathematics 2016-02-10 Kenneth R. Davidson , Matthew Kennedy

We prove that every surjective isometry from the unit sphere of the space $K(H),$ of all compact operators on an arbitrary complex Hilbert space $H$, onto the unit sphere of an arbitrary real Banach space $Y$ can be extended to a surjective…

Functional Analysis · Mathematics 2020-05-26 Antonio M. Peralta

The powerful concept of an operator ideal on the class of all Banach spaces makes sense in the real and in the complex case. In both settings we may, for example, consider compact, nuclear, or $2$--summing operators, where the definitions…

Functional Analysis · Mathematics 2016-09-06 Joerg Wenzel

A regular operator T on a Hilbert C^*-module is defined just like a closed operator on a Hilbert space, with the extra condition that the range of (I+T^*T) is dense. Semiregular operators are a slightly larger class of operators that may…

Operator Algebras · Mathematics 2007-05-23 Arupkumar Pal

A free semigroupoid algebra is the weak operator topology closed algebra generated by the left regular representation of a directed graph. We establish lattice isomorphisms between ideals and invariant subspaces, and this leads to a…

Operator Algebras · Mathematics 2007-05-23 Michael T. Jury , David W. Kribs

A semicrossed product is a non-selfadjoint operator algebra encoding the action of a semigroup on an operator or C*-algebra. We prove that, when the positive cone of a discrete lattice ordered abelian group acts on a C*-algebra, the…

Operator Algebras · Mathematics 2021-02-08 Adam Humeniuk