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I prove a local finite determinacy result of singular fibres in families. As an application, I generalize finite determinacy results on the fibres of log morphisms and nearby and vanishing cycles sheaves by Illusie and Kisin.

Algebraic Geometry · Mathematics 2019-09-10 Helge Ruddat

We prove that if the fundamental group of an arbitrary three-manifold -- not necessarily closed, nor orientable -- is a Kaehler group, then it is either finite or the fundamental group of a closed orientable surface.

Geometric Topology · Mathematics 2014-01-14 D. Kotschick

We give a construction of a family of locally finite residually finite groups with just-infinite C*-algebra. This answers a question from [2]. Additionally, we show that residually finite groups of finite exponent are never just-infinite.

Operator Algebras · Mathematics 2016-06-27 V. Belyaev , R. Grigorchuk , P. Shumyatsky

We explore connected affine algebraic groups $G$, which enjoy the following finiteness property $\rm (F)$: for every algebraic action of $G$, the closure of every $G$-orbit contains only finitely many $G$-orbits. We obtain two main results.…

Algebraic Geometry · Mathematics 2020-04-16 Vladimir L. Popov

We prove that infinite definably simple locally finite groups of finite centraliser dimension are simple groups of Lie type over locally finite fields. Then, we identify conditions on automorphisms of a stable group that make it resemble…

Logic · Mathematics 2019-06-12 Ulla Karhumäki

We determine all finite subgroups of simple algebraic groups that have irreducible centralizers - that is, centralizers whose connected component does not lie in a parabolic subgroup.

Group Theory · Mathematics 2016-06-10 Martin W. Liebeck , Adam R. Thomas

It is known from work by H. Abels and P. Abramenko that for a classical Fq-group G of rank n the arithemetic lattice G(Fq[t]) of Fq[t]-rational points is of type Fn-1 provided that q is large enough. We show that the statement is true…

Group Theory · Mathematics 2011-08-18 Kai-Uwe Bux , Ralf Köhl , Stefan Witzel

Let $p$ be a prime number, and let $k$ be an algebraically closed field of characteristic $p$. We show that the tame fundamental group of a smooth affine curve over $k$ is a projective profinite group. We prove that the fundamental group of…

Algebraic Geometry · Mathematics 2021-03-09 Hélène Esnault , Mark Shusterman , Vasudevan Srinivas

We classify projective terminalizations of quotients of Fano varieties of lines on smooth cubic fourfolds by finite groups of symplectic automorphisms of the underlying cubic. We compute the second Betti number and the fundamental group of…

Algebraic Geometry · Mathematics 2026-02-19 Enrica Mazzon

This is a companion paper to our previous work, where we proved the finiteness of the Tate-Shafarevich group for an arbitrary torus $T$ over a finitely generated field $K$ with respect to any divisorial set $V$ of places of $K$. Here, we…

Algebraic Geometry · Mathematics 2023-12-15 Andrei S. Rapinchuk , Igor A. Rapinchuk

In this paper, we study the fundamental group of a certain class of globally hyperbolic Lorentzian manifolds with a positive curvature tensor. We prove that the fundamental group of lightlike geodesically complete parametrized Lorentzian…

Differential Geometry · Mathematics 2014-09-04 Jun-ichi Mukuno

We formulate and analyze several finiteness conjectures for linear algebraic groups over higher-dimensional fields. In fact, we prove all of these conjectures for algebraic tori as well as in some other situations. This work relies in an…

Number Theory · Mathematics 2020-02-18 Andrei S. Rapinchuk , Igor A. Rapinchuk

In this report we summarize this work, all finite simple groups $G$ can determined uniformly using their orders $|G|$ and the set $\pi_e(G)$ of their element orders.

Group Theory · Mathematics 2013-03-19 Wujie Shi

We give a simple proof of a result originally due to Dimca and Suciu: a group that is both Kaehler and the fundamental group of a closed three-manifold is finite. We also prove that a group that is both the fundamental group of a closed…

Geometric Topology · Mathematics 2016-03-03 D. Kotschick

In this paper I consider locally finite Lie algebras of characteristic zero satisfying the condition that for every finite number of elements $x_{1}, x_{2},..., x_{k}$ of such an algebra $L$ there is finite-dimensional subalgebra $A$ which…

Rings and Algebras · Mathematics 2007-05-23 L. A. Simonian

In this paper we prove that free solvable groups have finite Krull dimension. In fact, this is true for much wider class of solvable groups, termed rigid groups. Along the way we study the algebraic structure of the limit solvable groups…

Group Theory · Mathematics 2008-08-22 A. Myasnikov , N. Romanovskiy

Let $G$ be a group. We denote by $\nu(G)$ a certain extension of the non-abelian tensor square $G \otimes G$ by $G \times G$. We prove that if $G$ is a finitely generated group in which the set of all simple tensors $T_{\otimes}(G)$ is…

Group Theory · Mathematics 2016-10-19 Raimundo Bastos , Noraí Romeu Rocco

We introduce the fundamental group $F(\mathcal{M})$ of a finite von Neumann algebra $\mathcal{M}$ with finite dimensional normal trace space. The form of $F(\mathcal{M})$ is completely determined. Moreover, there exists a finite von Neumann…

Operator Algebras · Mathematics 2016-08-24 Takashi Kawahara

Locally finite groups having the property that every non-cyclic subgroup contains its centralizer are completely classified.

Group Theory · Mathematics 2016-06-07 Costantino Delizia , Urban Jezernik , Primoz Moravec , Chiara Nicotera , Chris Parker

We prove that all Mathieu groups, some linear, and unitary groups are factorizable.

Group Theory · Mathematics 2020-06-16 Nurlan Gasimli