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Positive $C_0$-semigroups that occur in concrete applications are, more often than not, irreducible. Therefore a deep and extensive theory of irreducibility has been developed that includes characterizations, perturbation analysis, and…

Functional Analysis · Mathematics 2024-06-28 Sahiba Arora , Jochen Glück

Given a pair of dynamical systems we consider a pair of commuting von Neumann factors of type 11_1. The construction is a generalization of classical von Neumann-Murrey and grouppoid construction. It gives a natural examples of factors with…

Operator Algebras · Mathematics 2007-05-23 A. Vershik

We prove that every separable tracial von Neumann algebra embeds into a II$_1$ factor with property (T) which can be taken to have trivial outer automorphism and fundamental groups. We also establish an analogous result for the trivial…

Operator Algebras · Mathematics 2022-05-17 Ionut Chifan , Daniel Drimbe , Adrian Ioana

There is a natural construction which associates to a finitely generated, countable, discrete group $G$ and a 3-cocycle $\omega$ of $G$ an inclusion of II$_1$ factors, the so-called diagonal subfactors (with cocycle). In the case when the…

Operator Algebras · Mathematics 2008-12-30 Dietmar Bisch , Paramita Das , Shamindra Kumar Ghosh

We provide a family of group measure space II_1 factors for which all finite index subfactors can be explicitly listed. In particular, the set of all indices of irreducible subfactors can be computed. Concrete examples show that this index…

Operator Algebras · Mathematics 2011-11-29 Steven Deprez , Stefaan Vaes

We demonstrate von Neumann algebra arising from an icc group $\Gamma$ in Chifan's, Ioana's, and Kida's class of poly-$\mathcal{C}_\text{rss} $, such as a poly-hyperbolic group with no amenable factors in its composition series, satisfies…

Operator Algebras · Mathematics 2018-02-27 Rolando de Santiago , Sujan Pant

In the paper, we study the generator problem of II$_1$ factors. By defining a new concept related to the number of generators of a von Neumann algebra, we are able to show that a large class of II$_1$ factors are singly generated, i.e.,…

Operator Algebras · Mathematics 2007-05-23 Junhao Shen

Let Q be any II_1-factor. It is shown that any standard lattice G can be realized as the standard invariant of a free product of (several) rescalings of Q. In particular, if Q has fundamental group equal to the positive reals and if P is…

Operator Algebras · Mathematics 2007-05-23 Ken Dykema

For each $\lambda\in\left]0,1\right]$ we exhibit an uncountable family of compact quantum groups $\mathbb{G}$ such that the von Neumann algebra $\mathsf{L}^{\!\infty}(\mathbb{G})$ is the injective factor of type $\mathrm{III}_\lambda$ with…

Operator Algebras · Mathematics 2024-09-05 Jacek Krajczok , Piotr M. Sołtan

We introduce the notion of a generalized Jung factor: a II$_1$ factor $M$ for which any two embeddings of $M$ into its ultrapower $M^{\mathcal U}$ are equivalent by an automorphism of $M^{\mathcal U}$. We show that $\mathcal R$ is not the…

Operator Algebras · Mathematics 2020-05-13 Scott Atkinson , Isaac Goldbring , Srivatsav Kunnawalkam Elayavalli

For any finite dimensional C^*-algebra A, we give an endomorphism \Phi of the hyperfinite II_1 factor R of finite Jones index such that: for all k \in \mathbb {N}, \Phi^k (R)' \cap R= \otimes^k A. The Jones index [R: \Phi (R)]= (rank…

Operator Algebras · Mathematics 2007-05-23 Hsiang-Ping Huang

We prove that for any free ergodic probability measure preserving action \F_n \actson (X,\mu) of a free group on n generators \F_n, 2 \leq n \leq \infty, the associated group measure space II_1 factor $L^\infty(X) \rtimes \F_n$ has…

Operator Algebras · Mathematics 2014-03-21 Sorin Popa , Stefaan Vaes

We show that finitely generated irreducible $\mathrm{II}_1$ subfactors are generic in the following sense. Given a separable $\mathrm{II}_1$ factor $M$ and an integer $n\geq 2$, equip the set of $n$-tuples of self-adjoint operators in $M$…

Operator Algebras · Mathematics 2025-06-03 Yoonkyeong Lee , Brent Nelson

This paper studies how many orthogonal bi-invariant complex structures exist on a metric Lie algebra over the real numbers. Recently, it was shown that irreducible Lie algebras which are additionally $2$-step nilpotent admit at most one…

Differential Geometry · Mathematics 2020-07-20 Jonas Deré

We apply the notion of a full convex subcategory to a wide range of algebras including tilted, quasi-tilted, shod, weakly shod, left and right glued, laura, simply connected, strongly simply connected, left supported, and cluster-tilted. In…

Representation Theory · Mathematics 2020-06-30 Stephen Zito

We provide an alternative proof for the extreme amenability of the unitary group of the hyperfinite II${}_1$-factor von Neumann algebra, endowed with the strong operator topology.

Operator Algebras · Mathematics 2015-07-02 Philip A. Dowerk , Andreas Thom

We take the fundamental group of the complement of the branch curve of a generic projection induced from canonical embedding of a surface. This group is stable on connected components of moduli spaces of surfaces. Since for many classes of…

Algebraic Geometry · Mathematics 2007-05-23 Mina Teicher

This paper generalize [7](math.GT/0601291): We construct new links invariants from g, a type I basic classical Lie superalgebra. The construction uses the existence of an unexpected replacement of the vanishing quantum dimension of typical…

Geometric Topology · Mathematics 2007-10-01 Nathan Geer , Bertrand Patureau-Mirand

We show that a noncommutative dynamical system of the type that occurs in quantum theory can often be associated with a dynamical principle; that is, an infinitesimal structure that completely determines the dynamics. The nature of these…

funct-an · Mathematics 2008-02-03 William Arveson

We study equivalence relations and II_1 factors associated with (quotients of) generalized Bernoulli actions of Kazhdan groups. Specific families of these actions are entirely classified up to isomorphism of II_1 factors. This yields…

Operator Algebras · Mathematics 2008-04-04 Sorin Popa , Stefaan Vaes