Olga Varghese

activity

20112025

most citedFixed points for actions of Aut(Fn) on CAT(0) spaces

7 citations · 16 across the 17 of their papers we have counts for

collaborators

26 papers

math.GR2025

On the derived length of Dyer groups

Olga Varghese

By definition, a group $G$ is quasi-perfect, if $G$ is perfect or the commutator subgroup of $G$ is perfect. In this note we give a description of quasi-perfect Dyer groups by prop…

math.GR2023

The growth series of Dyer groups

Luis Paris, Olga Varghese

Graph products of cyclic groups and Coxeter groups are two families of groups that are defined by labeled graphs. The family of Dyer groups contains these both families and gives u…

math.GR2023

On quotients of Coxeter groups

Philip Möller, Olga Varghese

A group $G$ is said to be just infinite if $G$ itself is infinite but all proper quotients of $G$ are finite. We show that a Coxeter group $W_{Γ}$ is just infinite if and only if $Γ$ …

math.GR2023★ 1 cited

Steep uncountable groups

Samuel M. Corson, Alexander Olshanskii, Olga Varghese

We produce a simple group $G$ of cardinality $ℵ_{1}$ which is Artinian (every strictly descending chain of subgroups is finite), satisfies a Burnside law and such that for each…

math.GR2022

Narrow normal subgroups of Coxeter groups and of automorphism groups of Coxeter groups

Luis Paris, Olga Varghese

By definition, a group is called narrow if it does not contain a copy of a non-abelian free group. We describe the structure of finite and narrow normal subgroups in Coxeter groups…

math.GR2022

On normal subgroups in automorphism groups

Philip Möller, Olga Varghese

We describe the structure of virtually solvable normal subgroups in the automorphism group of a right-angled Artin group $Aut (A_{Γ})$ . In particular, we prove that a finite nor…

math.GR2022

A note on semicompleteness of graph products of abelian groups

Philip Möller, Olga Varghese

In this short note we prove that a graph product $G_{Γ}$ of finitely generated abelian groups is semicomplete -- that is the kernel of the natural homomorphism ${\rm Aut}(G_Γ)\to{\rm…

math.GR2022

On parabolic subgroups of Artin groups

Philip Möller, Luis Paris, Olga Varghese

Given an Artin group $A_{Γ}$ , a common strategy in the study of $A_{Γ}$ is the reduction to parabolic subgroups whose defining graphs have small diameter, i.e. showing that $A_{Γ}$ has a…

math.GR2021

Automatic continuity for groups whose torsion subgroups are small

Daniel Keppeler, Philip Möller, Olga Varghese

We prove that a group homomorphism $φ : L \to G$ from a locally compact Hausdorff group $L$ into a discrete group $G$ either is continuous, or there exists a normal open subgrou…

math.GR2020

Abstract group actions of locally compact groups on CAT(0) spaces

Philip Möller, Olga Varghese

We study abstract group actions of locally compact Hausdorff groups on CAT(0) spaces. Under mild assumptions on the action we show that it is continuous or has a global fixed point…

math.GR2020

Coxeter quotients of the automorphism group of a Coxeter group

Olga Varghese

We show that for a large class $W$ of Coxeter groups the following holds: Given a group $W_{Γ}$ in $W$ , the automorphism group $Aut (W_{Γ})$ virtually surjects…

math.GR2019

A Nunke type classification in the locally compact setting

Samuel M. Corson, Olga Varghese

In this short note we prove that a group G is lcH-slender -- that is, every abstract group homomorphism from a locally compact Hausdorff topological group to G has an open kernel -…

math.GR2019

On number of ends of graph products of groups

Olga Varghese

Given a finite simplicial graph $Γ = (V, E)$ with a vertex-labelling $φ : V \to {non-trivial finitely generated groups}$ , the graph product $G_{Γ}$ is the free p…

math.GR2019

Conjugating automorphisms of graph products: Kazhdan's property (T) and SQ-universality

Anthony Genevois, Olga Varghese

An automorphism of a graph product of groups is conjugating if it sends each factor to a conjugate of a factor (possibly different). In this article, we determine precisely when th…

math.GR2019

On hyperbolicity and virtual freeness of automorphism groups

Olga Varghese

We show that word hyperbolicity of automorphism groups of graph products $G_{Γ}$ and of Coxeter groups $W_{Γ}$ depends strongly on the shape of the defining graph $Γ$ . We also characte…

math.GR2019★ 1 cited

On property (T) for automorphism groups of graph products

Nils Leder, Olga Varghese

We show that the automorphism group of a graph product of finite groups $A u t (G_{Γ})$ has Kazhdan's property (T) if and only if $Γ$ is a complete graph.

math.GR2019

Abstract homomorphisms from locally compact groups to discrete groups

Linus Kramer, Olga Varghese

We show that every abstract homomorphism $φ$ from a locally compact group $L$ to a graph product $G_{Γ}$ , endowed with the discrete topology, is either continuous or $φ (L)$ lies in a…

math.GR2018★ 6 cited

A note on locally elliptic actions on cube complexes

Nils Leder, Olga Varghese

We deduce from Sageev's results that whenever a group acts locally elliptically on a finite dimensional CAT(0) cube complex, then it must fix a point. As an application, we give an…

math.GR2018

Planarity of Cayley graphs of graph products of groups

Olga Varghese

We obtain a complete classification of graph products of finite abelian groups whose Cayley graphs with respect to the standard presentations are planar.

math.GR2018

On coherence of graph products and Coxeter groups

Olga Varghese

We study coherence of graph products and Coxeter groups and obtain many results in this direction.

math.GR2018

The automorphism group of the universal Coxeter group

Olga Varghese

We study fixed point properties of the automorphism group of the universal Coxeter group Aut $(W_{n})$ . In particular, we prove that whenever Aut $(W_{n})$ acts by isometries on complete…

math.GR2018

Representations of groups with CAT(0) fixed point property

Olga Varghese

We show that certain representations over fields with positive characteristic of groups having CAT(0) fixed point property $F B_{A_{n}}$ have finite image.…

math.GR2015

SAut(Fn) cannot act on small tori

Olga Varghese

We study smooth actions of SAut(Fn), the unique subgroup of index two in the automorphism group of a free group of rank n, as a part of the generalized 'Zimmer program'. In particu…

math.GR2015★ 1 cited

Low dimensional linear representations of SAut(Fn)

Olga Varghese

We prove that SAut(Fn), the unique subgroup of index two in the automorphism group of a free group of rank n, admits no non-trivial linear representation of degree d<n for any fiel…