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We give a simple and unified proof showing that the unrestricted wreath product of a weakly sofic, sofic, linear sofic, or hyperlinear group by an amenable group is weakly sofic, sofic, linear sofic, or hyperlinear, respectively. By means…

Group Theory · Mathematics 2022-02-17 Javier Brude , Román Sasyk

We investigate the notion of soficity for monoids. A group is sofic as a group if and only if it is sofic as a monoid. All finite monoids, all commutative monoids, all free monoids, all cancellative one-sided amenable monoids, all…

Dynamical Systems · Mathematics 2015-05-06 Tullio Ceccherini-Silberstein , Michel Coornaert

Using the model theory of metric structures, I give an alternative proof of the following result by Thomas: If the Continuum Hypothesis fails then there are power of the continuum many universal sofic groups up to isomorphism. This method…

Logic · Mathematics 2016-05-06 Martino Lupini

We consider metric ultraproducts of finite groups with respect to some classes of length functions. All sofic groups embed into these ultraproducts. We study embeddings of normed groups. We also show that in some natural situations such an…

Group Theory · Mathematics 2014-01-07 A. Ivanov

We introduce and study soficity for Lie algebras, modelled after linear soficity in associative algebras. We introduce equivalent definitions of soficity, one involving metric ultraproducts and the other involving almost representations. We…

Rings and Algebras · Mathematics 2022-03-14 Cameron Cinel

Sofic groups generalise both residually finite and amenable groups, and the concept is central to many important results and conjectures in measured group theory. We introduce a topological notion of a sofic boundary attached to a given…

Group Theory · Mathematics 2026-04-28 Vadim Alekseev , Martin Finn-Sell

A countable group G is called k-linear sofic (for some 0 <k \le 1) if finite subsets of G admit "approximate representations" by complex invertible matrices in the normalized rank metric, so that non-identity elements are k-away from the…

Group Theory · Mathematics 2025-04-02 Keivan Mallahi-Karai , Maryam Mohammadi Yekta

We prove that a monoid is sofic, in the sense recently introduced by Ceccherini-Silberstein and Coornaert, whenever the J-class of the identity is a sofic group, and the quotients of this group by orbit stabilisers in the rest of the monoid…

Group Theory · Mathematics 2014-01-29 Mark Kambites

We introduce the notion of a ``sofic $\mathcal{C}$-action'' of one group on another by automorphisms, for $\mathcal{C}$ a class of groups. We show that if $\mathcal{C}$ is the class of (i) sofic, (ii) hyperlinear, (iii) linear sofic or (iv)…

Group Theory · Mathematics 2026-01-27 Vadim Alekseev , Henry Bradford

We define a notion of relative soficity for countable groups with respect to a family of groups. A group is sofic if and only if it is relative sofic with respect to the family consisting only of the trivial group. If a group is relatively…

Group Theory · Mathematics 2019-01-11 Ronghui Ji , Crichton Ogle , Bobby Ramsey

In continuous logic, there are plenty of examples of interesting stable metric structures. However, on the other side of the SOP line, there are only a few metric structures where order is relevant, and orders often appear in different…

Logic · Mathematics 2025-10-15 Aaron Anderson , Diego Bejarano

In this paper, we introduce a symmetric continuous cohomology of topological groups. This is obtained by topologizing a recent construction due to Staic (J. Algebra 322 (2009), 1360-1378), where a symmetric cohomology of abstract groups is…

Group Theory · Mathematics 2013-06-04 Mahender Singh

We initiate the study of pseudofiniteness in continuous logic. We introduce a related concept, namely that of pseudocompactness, and investigate the relationship between the two concepts. We establish some basic properties of…

Logic · Mathematics 2016-02-10 Isaac Goldbring , Vinicius Cifu Lopes

We provide a quantitative formulation of the equivalence between hyperlinearity and soficity for amenable groups, showing that every hyperlinear approximation to such a group is essentially produced from a sofic approximation. This…

Group Theory · Mathematics 2023-11-17 Peter Burton

We introduce the class of strongly sofic monoids. This class of monoids strictly contains the class of sofic groups and is a proper subclass of the class of sofic monoids. We define and investigate sofic topological entropy for actions of…

Group Theory · Mathematics 2025-02-10 Tullio Ceccherini-Silberstein , Michel Coornaert , Xuan Kien Phung

We give an example of a sofic group, which is not a limit of amenable groups.

Group Theory · Mathematics 2011-05-17 Yves Cornulier

We construct an analogue of Neumann's affiliated algebras for sofic group algebras over arbitrary fields. Consequently, we settle Kaplansky's direct finiteness conjecture for sofic groups.

Rings and Algebras · Mathematics 2007-05-23 G. Elek , E. Szabo

We consider metric versions of the notions of local embeddability and LEF. We pay special attention to normally finitely generated groups with word metrics.

Group Theory · Mathematics 2023-11-29 Aleksander Ivanov , Ireneusz Sobstyl

We study the notion of linear sofic approximations for algebras, analogous to the concept of sofic representations for groups. We prove that for a finitely generated amenable $K$-algebra with no zero divisors, all linear sofic…

Rings and Algebras · Mathematics 2026-05-28 Benjamin Bachner

A survey of problems, conjectures, and theorems about quasi-isometric classification and rigidity for finitely generated solvable groups.

Group Theory · Mathematics 2007-05-23 Benson Farb , Lee Mosher