Linear sofic groups and algebras

Injective Linear Cellular Automata and Sofic Groups

Let V be a finite-dimensional vector space over a field K and let G be a sofic group. We show that every injective linear cellular automaton τ : V G → V G is surjective. As an application, we obtain a new proof of the stable finiteness of group rings of sofic groups, a result previously established by G. Elek and A. Szabó using different methods.

Sofic groups and convolution operators

Conjecture: Let Γ be a discrete group, f ∈ L(Γ) and Tf : L (Γ) → L(Γ) be the right convolution by f . Then if Tf is injective, it is surjective as well. We prove the conjecture for the class of sofic groups. AMS Subject Classification: 43A20

Sofic Groups and Diophantine Approximation

We prove the algebraic eigenvalue conjecture of J.Dodziuk, P.Linnell, V.Mathai, T.Schick and S.Yates (see [2]) for sofic groups. Moreover, we give restrictions on the spectral measure of elements in the integral group ring. Finally, we prove a quantization of the operator norm below 2. To the knowledge of the author, there is no group known, which is not sofic.

Lie Algebras and their corresponding linear groups

An Introduction to Hyperlinear and Sofic Groups

These is an edited write-up of lecture notes of the 7-th Appalachian set theory workshop of the same title led by the first named author at the Cornell University on November 22, 2008. A draft version of the notes was prepared by the second named author. This presentation is largely complementary to the earlier survey by the first-named author (Hyperlinear and sofic groups: a brief guide, Bull....