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We develop the foundations of the deformation theory of compact complete affine space forms and affine crystallographic groups. Using methods from the theory of linear algebraic groups we show that these deformation spaces inherit an…

Differential Geometry · Mathematics 2008-09-05 Oliver Baues

The reality of the difficulties in investigation of finite groups are considered. It is shown that the consideration of symmetry properties of the $k$-orbits that are obtained with an action of a finite group $F=(V,\cdot)$ on Cartesian…

General Mathematics · Mathematics 2007-05-23 Aleksandr Golubchik

By the work of Brodzki-Niblo-Nowak-Wright and Monod, topological amenability of a continuous group action can be characterized using uniformly finite homology groups or bounded cohomology groups associated to this action. We show that…

Dynamical Systems · Mathematics 2021-08-11 Yongle Jiang

In this note we introduce and characterize a class of finite groups for which the element orders satisfy a certain inequality. This is contained in some well-known classes of finite groups.

Group Theory · Mathematics 2018-05-24 Marius Tărnăuceanu

A notion of degeneration of elements in groups is introduced. It is used to parametrize the orbits in a finite abelian group under its full automorphism group by a finite distributive lattice. A pictorial description of this lattice leads…

Group Theory · Mathematics 2011-03-02 Kunal Dutta , Amritanshu Prasad

We describe the primitive central idempotents of the group algebra over a number field of finite monomial groups. We give also a description of the Wedderburn decomposition of the group algebra over a number field for finite strongly…

Representation Theory · Mathematics 2014-11-24 Gabriela Olteanu , Inneke Van Gelder

We study deformations of the discrete Heisenberg group acting properly discontinuously on the Heisenberg group from the left and right and obtain a complete description of the deformation space.

Group Theory · Mathematics 2023-03-28 Severin Barmeier

This is an expository article on properties of actions on Lie groups by subgroups of their automorphism groups. After recalling various results on the structure of the automorphism groups, we discuss actions with dense orbits, invariant and…

Group Theory · Mathematics 2017-03-29 S. G. Dani

We introduce some compact orbifolds on which there is a certain finite group action having a simple convex polytope as the orbit space. We compute the orbifold fundamental group and homology groups of these orbifolds. We calculate the…

Algebraic Topology · Mathematics 2011-05-10 Soumen Sarkar

We introduce asymptotically rigid mapping class groups of handlebodies and determine their finiteness properties, which vary depending on the space of ends of the underlying handlebody. As it turns out, in some cases, the homology of these…

Geometric Topology · Mathematics 2025-04-09 Sergio Domingo-Zubiaga

Let G be the homeomorphism group of a dendrite. We study the normal subgroups of G. For instance, there are uncountably many non-isomorphic such groups G that are simple groups. Moreover, these groups can be chosen so that any isometric…

Group Theory · Mathematics 2021-02-03 Bruno Duchesne , Nicolas Monod

We use methods from the cohomology of groups to describe the finite groups which can act freely and homologically trivially on closed 3-manifolds which are rational homology spheres.

Algebraic Topology · Mathematics 2019-08-16 Alejandro Adem , Ian Hambleton

We generalize the notion of isoperimetric profiles of finitely generated groups to their actions by measuring the boundary of finite subgraphings of the orbit graphing. We prove that like the classical isoperimetric profiles for groups,…

Dynamical Systems · Mathematics 2023-10-05 Zihan Xia

Dendriform algebras are certain associative algebras whose product splits into two binary operations and the associativity splits into three new identities. In this paper, we study finite group actions on dendriform algebras. We define…

Rings and Algebras · Mathematics 2022-08-02 Apurba Das , Ripan Saha

We survey the existing parts of a classification of finite groups generated by orthogonal transformations in a finite-dimensional Euclidean space whose fixed point subspace has codimension one or two and extend it to a complete…

Group Theory · Mathematics 2017-11-02 Christian Lange , Marina A. Mikhailova

This is a survey on upper and lower bounds for finite group actions on bounded surfaces, 3-dimensional handlebodies and closed handles, handlebodies in arbitrary dimensions and finite graphs (the common feature of these objects is that all…

Geometric Topology · Mathematics 2016-04-25 Bruno P. Zimmermann

We study simplicial action of groups on one vertex Kan complexes. We show that every semi-direct product of the fundamental group of an one vertex Kan complex with a finite group can be simplicially realized. We also calculate the…

Algebraic Topology · Mathematics 2013-08-15 Goutam Mukherjee , Swagata Sarkar , Debasis Sen

We introduce an equivariant version of Hochschild cohomology as the deformation cohomology to study equivariant deformations of associative algebras equipped with finite group actions.

Rings and Algebras · Mathematics 2018-04-17 Goutam Mukherjee , Raj Bhawan Yadav

To any finite ordered subset and any finite partition of a group a set of tuples of positive integers, named as configurations, is associated that describes the group's behavior. The present paper provides an exposition of this notion and…

Group Theory · Mathematics 2018-04-24 Akram Yousofzadeh

In this note some properties of the sum of element orders of a finite abelian group are studied.

Group Theory · Mathematics 2018-05-31 Marius Tărnăuceanu , Dan Gregorian Fodor