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We consider the actions of (semi)groups on a locally compact group by automorphisms. We show the equivalence of distality and pointwise distality for the actions of a certain class of groups. We also show that a compactly generated locally…

Dynamical Systems · Mathematics 2019-03-27 C. R. E. Raja , Riddhi Shah

We classify representations of compact connected Lie groups whose induced action on the unit sphere has an orbit space isometric to a Riemannian orbifold.

Differential Geometry · Mathematics 2017-03-14 Claudio Gorodski , Alexander Lytchak

We prove that the solid ergodicity property is stable with respect to taking coinduction for a fairly large class of coinduced action. More precisely, assume that $\Sigma<\Gamma$ are countable groups such that $g\Sigma g^{-1}\cap \Sigma$ is…

Dynamical Systems · Mathematics 2020-10-21 Daniel Drimbe

In contrast to classical strongly continuous semigroups, the study of bi-continuous semigroups comes with some freedom in the properties of the associated locally convex topology. This paper aims to give minimal assumptions in order to…

Functional Analysis · Mathematics 2023-07-19 Karsten Kruse , Felix L. Schwenninger

We prove that a connected locally compact median space of finite rank which admits a transitive action is isometric to $\mathbb{R}^n$ endowed with the $\ell^1$-metric. In the other side, replacing the transitivity assumption on the group of…

Geometric Topology · Mathematics 2024-03-07 Mohamed Lamine Messaci

An action of a topological semigroup S on X is compactifiable if this action is a restriction of a jointly continuous action of S on a Hausdorff compact space Y. A topological semigroup S is compactifiable if the left action of S on itself…

General Topology · Mathematics 2007-05-23 Michael Megrelishvili

To any action of a compact quantum group on a von Neumann algebra which is a direct sum of factors we associate an equivalence relation corresponding to the partition of a space into orbits of the action. We show that in case all factors…

Operator Algebras · Mathematics 2019-01-29 Kenny De Commer , Paweł Kasprzak , Adam Skalski , Piotr M. Sołtan

Quasi-invariant measures for non-discrete groups of diffeomorphisms containing a Morse-Smale dynamics are studied. The assumption concerning the presence of a Morse-Smale dynamics allows us to extend to higher dimensions a number of…

Dynamical Systems · Mathematics 2013-03-27 Julio C. Rebelo

The author proposes a method for investigating actions of finite groups on aspherical spaces. Complete homotopy classification of free actions of finite groups on aspherical spaces is obtained. Also there are some results about non-free…

General Topology · Mathematics 2010-09-01 Lev Lokutsievskiy

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

In this work we present a principle which says that quasimorphisms can be obtained via "local data" of the group action on certain appropriate spaces. In a rough manner the principle says that instead of starting with a given group and try…

Group Theory · Mathematics 2012-01-31 Gabi Ben Simon

We extend recent orbit counts for finitely generated semigroups acting on $\mathbb{P}^N$ to certain infinitely generated, polarized semigroups acting on projective varieties. We then apply these results to semigroup orbits generated by some…

Number Theory · Mathematics 2021-01-01 Wade Hindes

The group of continuous binary operations on a topological space is studied; its relationship with the group of homeomorphisms is established. The category of binary $G$-spaces and bi-equivariant maps is constructed, which is a natural…

General Topology · Mathematics 2023-07-13 Pavel S. Gevorgyan

We consider a new orbit equivalence invariant for measure-preserving actions of groups on the probability space, $\sigma:G\to$ Aut$(X,\mu)$, denoted $\chi_0(\sigma;G)$ and defined as the "intersection" of the 1-cohomology group,…

Operator Algebras · Mathematics 2007-05-23 Adrian Ioana

In this study we introduce the notions of semi-homotopy of semi-continuous maps and of semi-paths. We also construct a group structure, which will be called semi-fundamental group, using semi-loops and explore some properties of…

Algebraic Topology · Mathematics 2016-04-27 Ayhan Erciyes , Ali Aytekin , Tunçar Şahan

We study self-adjoint semigroups of partial isometries on a Hilbert space. These semigroups coincide precisely with faithful representations of abstract inverse semigroups. Groups of unitary operators are specialized examples of…

Functional Analysis · Mathematics 2013-06-13 Alexey I. Popov , Heydar Radjavi

We initiate the study of group actions on (possibly infinite) semimatroids and geometric semilattices. To every such action is naturally associated an orbit-counting function, a two-variable "Tutte" polynomial and a poset which, in the…

Combinatorics · Mathematics 2017-02-23 Emanuele Delucchi , Sonja Riedel

In this paper we study a subclass of subcartesian space-the orbit space of a proper action of Lie group on smooth manifold. We show that continuous functions on orbit space can be approximated by smooth functions.

Differential Geometry · Mathematics 2021-11-22 Qianqian Xia

In this article we consider a restricted orbital counting problem for the action of certain discrete groups on suitable spaces. In particular, we present asymptotics for counting those points in an orbit restricted to a single conjugacy…

Dynamical Systems · Mathematics 2026-05-08 Alexander Baumgartner , Mark Pollicott

In this paper we study the separately continuous actions of semitopological monoids on pseudocompact spaces. The main aim of this paper is to generalize Lawson's results to some class of pseudocompact spaces. Also, we introduce a concept of…

General Topology · Mathematics 2023-11-14 Alexander V. Osipov , Konstantin Kazachenko