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The groups distinguish their von Neumann algebras, in the case when these are factors.

Operator Algebras · Mathematics 2015-05-21 Sa Ge Lee

We derive atomic decompositions and frames for weighted Bergman spaces of several complex variables on the unit ball in the spirit of Coifman, Rochberg, and Luecking. In contrast to our predecessors, we use group theoretic methods, in…

Complex Variables · Mathematics 2015-04-03 Jens Christensen , Karlheinz Gröchenig , Gestur Ólafsson

We study whether a unital associative algebra $ A $ over a field admits a decomposition of the form $A = Z(A) + [A,A]$ where $ Z(A) $ is the center of $ A $ and $ [A,A] $ denotes the additive subgroup of $A$ generated by all additive…

Rings and Algebras · Mathematics 2025-05-20 Nguyen Thi Thai Ha , Tran Nam Son , Pham Duy Vinh

A unitary family is a family of unitary operators $U(x)$ acting on a finite dimensional hermitian vector space, depending analytically on a real parameter $x$. It is monotone if $\frac1i U'(x)U(x)^{-1}$ is a positive operator for each $x$.…

Functional Analysis · Mathematics 2007-11-20 Daniel Grieser

In this talk, I will survey recent progress made on the classification of von Neumann algebras arising from countable groups and their actions on probability spaces. In particular, I will present the first results which provide classes of…

Operator Algebras · Mathematics 2012-12-04 Adrian Ioana

We study the algebras generated by restriction and induction operations on complex modules over dihedral groups. In the case where the orders of all dihedral groups involved are not divisible by four, we describe the relations, a basis, the…

Representation Theory · Mathematics 2018-05-08 Brendan Dubsky

In an attempt to create an algebraic framework for dual canonical bases and total positivity in semisimple groups, we initiate the study of a new class of commutative algebras.

Representation Theory · Mathematics 2007-05-23 Sergey Fomin , Andrei Zelevinsky

We study the modular representation theory of the symmetric and alternating groups. One of the most natural ways to label the irreducible representations of a given group or algebra in the modular case is to show the unitriangularity of the…

Representation Theory · Mathematics 2020-12-09 Olivier Brunat , Jean-Baptiste Gramain , Nicolas Jacon

In this article we study in detail the category of noncommutative motives of separable algebras Sep(k) over a base field k. We start by constructing four different models of the full subcategory of commutative separable algebras CSep(k).…

Algebraic Geometry · Mathematics 2014-12-16 Goncalo Tabuada , Michel Van den Bergh

Decompositions of the unitary group U(n) are useful tools in quantum information theory as they allow one to decompose unitary evolutions into local evolutions and evolutions causing entanglement. Several recursive decompositions have been…

Quantum Physics · Physics 2009-11-13 Mehmet Dagli , Domenico D'Alessandro , Jonathan D. H. Smith

In this article, we study the derivations of group algebras of some important groups, namely, dihedral ($D_{2n}$), Dicyclic ($T_{4n}$) and Semi-dihedral ($SD_{8n}$). First, we explicitly classify all inner derivations of a group algebra…

Rings and Algebras · Mathematics 2024-10-06 Praveen Manju , Rajendra Kumar Sharma

We prove a canonical Kunneth decomposition for the motive of a commutative group scheme over a field. Moreover, we show that this decomposition behaves under the group law just as in cohomology. We also deduce applications of the…

Algebraic Geometry · Mathematics 2016-03-18 Giuseppe Ancona , Stephen Enright-Ward , Annette Huber

This note will present a new proof of the fact that every uniformly bounded group of invertible elements in a finite von Neumann algebra is similar to a unitary group. The proof involves metric geometric arguments in the non-positively…

Operator Algebras · Mathematics 2017-05-04 Martin Miglioli

We survey some of the progress made recently in the classification of von Neumann algebras arising from countable groups and their measure preserving actions on probability spaces. We emphasize results which provide classes of…

Operator Algebras · Mathematics 2017-12-04 Adrian Ioana

A reduction formula for compressions of von Neumann algebras arising as free products is proved. This shows that the fundamental group is all of the positive reals for some such algebras. Additionally, by taking a sort of free product with…

Operator Algebras · Mathematics 2007-05-23 Ken Dykema , Florin Radulescu

The unipotent groups are an important class of algebraic groups. We show that techniques used to compute with finitely generated nilpotent groups carry over to unipotent groups. We concentrate particularly on the maximal unipotent subgroup…

Group Theory · Mathematics 2007-05-23 Arjeh M. Cohen , Sergei Haller , Scott H. Murray

We define a notion of a weak canonical base for a partial type. This notion is weaker than the usual canonical base for an amalgamation base. We prove that certain family of partial types have a weak canonical base. This family clearly…

Logic · Mathematics 2013-11-14 Ziv Shami

We give a combinatorial description (including explicit differential-form bases) for the cohomology groups of the space of n distinct nonzero complex numbers, with coefficients in rank-one local systems which are of finite monodromy around…

Representation Theory · Mathematics 2007-05-23 Anthony Henderson

We construct families of commutative (super) algebra objects in the category of weight modules for the unrolled restricted quantum group $\overline{U}_q^H(\mfg)$ of a simple Lie algebra $\mfg$ at roots of unity, and study their categories…

Representation Theory · Mathematics 2020-05-27 Thomas Creutzig , Matthew Rupert

We study fundamental groups of algebraic stacks. We show that these fundamental groups carry an additional structure coming from the inertia groups. Then use this additional structure to analyze geometric/ topological properties of stacks.…

Algebraic Geometry · Mathematics 2007-05-23 Behrang Noohi
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