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We establish the MF property of the reduced group $ C^* $-algebra of an amalgamated free product of countable Abelian discrete groups. This result is then used to give a characterization of the amalgamated free products of Abelian groups…

Operator Algebras · Mathematics 2011-05-04 Jonas Andersen Seebach

We establish a platform to transfer $L_p$-completely bounded maps on tensor products of von Neumann algebras to $L_p$-completely bounded maps on the corresponding amalgamated free products. As a consequence, we obtain a H\"ormander-Mikhlin…

Operator Algebras · Mathematics 2021-03-18 Tao Mei , Éric Ricard , Quanhua Xu

We develop a new approach on free wreath products, generalizing the constructions of Bichon and of Fima-Pittau. We show stability properties for certain approximation properties such as exactness, Haagerup property, hyperlinearity and…

Operator Algebras · Mathematics 2025-04-02 Pierre Fima , Arthur Troupel

Let $I$ be any nonempty set and $(M_i, \varphi_i)_{i \in I}$ any family of nonamenable factors, endowed with arbitrary faithful normal states, that belong to a large class $\mathcal C_{\rm anti-free}$ of (possibly type III) von Neumann…

Operator Algebras · Mathematics 2019-02-20 Cyril Houdayer , Yoshimichi Ueda

We study the space of traces associated with arbitrary full free products of unital, separable $C^*$-algebras. We show that, unless certain basic obstructions (which we fully characterize) occur, the space of traces always results in the…

Operator Algebras · Mathematics 2024-12-19 Adrian Ioana , Pieter Spaas , Itamar Vigdorovich

We define a notion of free product for coarse spaces that generalizes the corresponding notion of a free product for groups. We show that free products preserve coarse properties such as coarse property C, finite coarse decomposition…

Geometric Topology · Mathematics 2020-06-26 Greg Bell , Austin Lawson

We prove rigidity properties for von Neumann algebraic graph products. We introduce the notion of rigid graphs and define a class of II$_1$-factors named $\mathcal{C}_{\rm Rigid}$. For von Neumann algebras in this class we show a unique…

Operator Algebras · Mathematics 2026-05-13 Matthijs Borst , Martijn Caspers , Enli Chen

We study the generalized free wreath product of classical groups introduced by the first author and Arthur Troupel. We give an explicit computation of the Haar state and deduce important properties of their associated operator algebra: in…

Operator Algebras · Mathematics 2025-12-15 Pierre Fima , Yigang Qiu

Several techniques together with some partial answers are given to the questions of factoriality, type classification and fullness for amalgamated free product von Neumann algebras.

Operator Algebras · Mathematics 2019-05-21 Yoshimichi Ueda

Certain reduced free products of C*-algebras, (A,phi)=(A_1,phi_1)*(A_2,\phi_2), taken with respect to faithful states, at least one of which is not a trace, are shown to be purely infinite and simple. It is assumed that one of the A_i…

Operator Algebras · Mathematics 2007-05-23 Ken Dykema

Voiculescu's random matrix model for freeness is extended to the non-Gaussian case and also the case of constant block diagonal matrices. Thus we are able to investigate free products of free group factors with matrix algebras and with the…

funct-an · Mathematics 2016-08-31 Ken Dykema

We investigate free products of finite dimensional $C^*$-algebras with amalgamation over diagonal subalgebras. We look to determine under what circumstances a given free product is exact and/or nuclear. In some cases we find a description…

Operator Algebras · Mathematics 2013-07-23 Benton L. Duncan

We find a necessary and sufficient conditions for the simplicity and uniqueness of trace for reduced free products of finite families of finite dimensional $C^*$-algebras with specified traces on them.

Operator Algebras · Mathematics 2007-05-23 Nikolay A Ivanov

We prove that the free product pair of any finitely many copies of the unique amenable type III$_1$ factor endowed with weakly mixing states remembers the number of free components and the given states.

Operator Algebras · Mathematics 2020-09-14 Yoshimichi Ueda

We study Cartan subalgebras in the context of amalgamated free product II$_1$ factors and obtain several uniqueness and non-existence results. We prove that if $\Gamma$ belongs to a large class of amalgamated free product groups (which…

Operator Algebras · Mathematics 2014-09-11 Adrian Ioana

Let $(M, \varphi) = (M_1, \varphi_1) \ast (M_2, \varphi_2)$ be the free product of any $\sigma$-finite von Neumann algebras endowed with any faithful normal states. We show that whenever $Q \subset M$ is a von Neumann subalgebra with…

Operator Algebras · Mathematics 2016-10-05 Cyril Houdayer , Yoshimichi Ueda

Graph products for groups were defined by Green in her thesis as a generalization of both Cartesian and free products. In this paper we define the corresponding graph product for reduced and maximal C*-algebras, von Neumann algebras and…

Operator Algebras · Mathematics 2020-02-17 Martijn Caspers , Pierre Fima

In this paper we describe the amalgamated free product of finite and semifinite hyperfinite von Neumann algebras over atomic type I subalgebras. To do this we extend the notions of free dimension and standard embeddings used in the related…

Operator Algebras · Mathematics 2013-10-08 Daniel Redelmeier

The category of $C^*$-algebras is blessed with many different tensor products. In contrast, virtually the only tensor product ever used in the category of von Neumann algebras is the normal spatial tensor product. We propose a definition of…

Operator Algebras · Mathematics 2015-06-05 Matthew Wiersma

We are able to explicitly compute the bimodule structure of von Neumann algebra inclusions in handle constructions, which arise as inductive limits of iterated amalgamated free products not elementarily equivalent to $L(\mathbb{F}_2)$. Our…

Operator Algebras · Mathematics 2026-02-03 David Gao , David Jekel , Srivatsav Kunnawalkam Elayavalli , Gregory Patchell