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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

For $p,q\in [1,\infty)$, we study the isomorphism problem for the $p$- and $q$-convolution algebras associated to locally compact groups. While it is well known that not every group can be recovered from its group von Neumann algebra, we…

Functional Analysis · Mathematics 2018-10-03 Eusebio Gardella , Hannes Thiel

We show that the class MIP* of languages that can be decided by a classical verifier interacting with multiple all-powerful quantum provers sharing entanglement is equal to the class RE of recursively enumerable languages. Our proof builds…

Quantum Physics · Physics 2022-11-07 Zhengfeng Ji , Anand Natarajan , Thomas Vidick , John Wright , Henry Yuen

We show that Connes' embedding conjecture on von Neumann algebras is equivalent to the existence of certain algebraic certificates for a polynomial in noncommuting variables to satisfy the following nonnegativity condition: The trace is…

Operator Algebras · Mathematics 2011-04-19 Igor Klep , Markus Schweighofer

The subalgebra membership problem is the problem of deciding if a given element belongs to an algebra given by a set of generators. This is one of the best established computational problems in algebra. We consider a variant of this…

Logic in Computer Science · Computer Science 2023-06-22 Andrei Bulatov , Peter Mayr , Ágnes Szendrei

We give a modification of I. Klep and M. Schweighofer algebraic reformulation of Connes' embedding problem by considering *-algebra of the countably generated free group. This allows to consider only quadratic polynomials in unitary…

Operator Algebras · Mathematics 2013-06-11 Kate Juschenko , Stanislav Popovych

This is a detailed survey on the QWEP conjecture and Connes' embedding problem. Most of contents are taken from Kirchberg's paper [Invent. Math. 112 (1993)].

Operator Algebras · Mathematics 2007-05-23 Narutaka Ozawa

The $C^{\ast}$-algebra $\mathcal{U}_{nc}(n)$ is the universal $C^{\ast}$-algebra generated by $n^2$ generators $u_{ij}$ that make up a unitary matrix. We prove that Kirchberg's formulation of Connes' embedding problem has a positive answer…

Operator Algebras · Mathematics 2018-01-11 Samuel J. Harris

The longstanding nonnegative inverse eigenvalue problem (NIEP) is to determine which multisets of complex numbers occur as the spectrum of an entry-wise nonnegative matrix. Although there are some well-known necessary conditions, a solution…

Spectral Theory · Mathematics 2025-08-04 Charles R. Johnson , Pietro Paparella

A classic theorem of T. Ando characterises operators that have numerical radius at most one as operators that admit a certain positive 2x2 operator matrix completion. In this paper we consider variants of Ando's theorem, in which the…

Operator Algebras · Mathematics 2012-03-20 Douglas Farenick , Ali S. Kavruk , Vern I. Paulsen

More precisely, we give a simple and very short proof of "the Connes embedding problem implies the synchronous Tsirelson conjecture" that relies on only two elementary ingredients: 1) the well-known description of synchronous correlations…

Operator Algebras · Mathematics 2022-09-19 Alexander Frei

In this note, we show that the theory of tracial von Neumann algebras does not have a model companion. This will follow from the fact that the theory of any locally universal, McDuff II_1 factor does not have quantifier elimination. We also…

Logic · Mathematics 2012-07-30 Isaac Goldbring , Bradd Hart , Thomas Sinclair

We prove that every positive trace on a countably generated *-algebra can be approximated by positive traces on algebras of generic matrices. This implies that every countably generated tracial *-algebra can be embedded into a metric…

Operator Algebras · Mathematics 2010-05-06 Tim Netzer , Andreas Thom

Relations among von Neumann entropies of different parts of an $N$-partite quantum system have direct impact on our understanding of diverse situations ranging from spin systems to quantum coding theory and black holes. Best formulated in…

Quantum Physics · Physics 2024-01-03 Matthias Christandl , Bergfinnur Durhuus , Lasse Harboe Wolff

We introduce "embedding dimensions" of a family of generators of a finite von Neumann algebra when the von Neumann algebra can be faithfully embedded into the ultrapower of the hyperfinite II$_1$ factor. These embedding dimensions are von…

Operator Algebras · Mathematics 2007-05-23 Junhao Shen

Let $M$ be a $II_1$-factor with trace $\tau$, the linear subspaces of $L^2(M,\tau)$ are not just common Hilbert spaces, but they have additional structure. We introduce the notion of a cyclic linear space by taking those properties as…

Operator Algebras · Mathematics 2013-09-18 Valerio Capraro , Florin Radulescu

We prove a non-commutative version of the Hilbert's 17th problem, giving a characterization of the class of non-commutative polynomials in n-undeterminates that have positive trace when evaluated in n-selfadjoint elements in arbitrary II1…

Operator Algebras · Mathematics 2007-05-23 Florin Radulescu

We show that any II$_1$ factor that has the same 4-quantifier theory as the hyperfinite II$_1$ factor $\mathcal{R}$ satisfies the conclusion of the Popa Factorial Commutant Embedding Problem (FCEP) and has the Brown property. These results…

Operator Algebras · Mathematics 2020-07-24 Isaac Goldbring , Bradd Hart

We say that a $C^*$-algebra $\mathcal{A}$ satisfies the similarity property ((SP)) if every bounded homomorphism $u\colon \mathcal{A} \to \mathcal{B}(\mathit{H})$, where $\mathit{H}$ is a Hilbert space, is similar to a $*$-homomorphism. We…

Operator Algebras · Mathematics 2024-04-04 E. Papapetros

We study which von Neumann algebras can be embedded into uniform Roe algebras and quasi-local algebras associated to a uniformly locally finite metric space $X$. Under weak assumptions, these $\mathrm{C}^*$-algebras contain embedded copies…

Operator Algebras · Mathematics 2023-02-20 Florent P. Baudier , Bruno de Mendonça Braga , Ilijas Farah , Alessandro Vignati , Rufus Willett