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We show that the outer automorphism group of a polycyclic-by-finite group is an arithmetic group. This result follows from a detailed structural analysis of the automorphism groups of such groups. We use an extended version of the theory of…

Group Theory · Mathematics 2007-05-23 Oliver Baues , Fritz Grunewald

A description of group automorphisms of all two-dimensional algebras, considered up to isomorphism, over any basic field is provided.

Rings and Algebras · Mathematics 2024-11-19 Sh. Eshmirzayev , U. Bekbaev

A monomial algebra B is defined as a quotient of a polynomial ring by a monomial ideal, which is an ideal generated by a finite set of monomials. In this paper, we determine the automorphism group of a monomial algebra B, under the…

Algebraic Geometry · Mathematics 2026-04-28 Roberto Díaz , Alvaro Liendo , Gonzalo Manzano-Flores , Andriy Regeta

We give elementary proofs of the following two theorems on automorphisms of a finite group G: (1) An automorphism of G is inner if and only if it extends to an automorphism of every finite group containing G. (2) There exists a finite…

Group Theory · Mathematics 2024-05-07 Benjamin Sambale

This paper is devoted to a study of the automorphism groups of three series of finite dimensional special odd Hamiltonian superalgebras $\mathfrak{g}$ over a field of prime characteristic. Our aim is to characterize the connections between…

Rings and Algebras · Mathematics 2013-04-25 Liming Tang , Wende Liu

In this paper we discuss the existence of certain classes of cuspidal automorphic representations having non-zero Fourier coefficients for general semisimple algebraic group $G$ defined over a number field $k$ such that its Archimedean…

Number Theory · Mathematics 2015-05-27 Allen Moy , Goran Muić

For reductive groups $G$ over a number field we discuss automorphic liftings from cuspidal irreducible automorphic representations $\pi$ of $G(\mathbb{A})$ to cuspidal irreducible automorphic representations on $H(\mathbb{A})$ for the…

Representation Theory · Mathematics 2023-06-22 Mirko Rösner , Rainer Weissauer

We investigate the action of the automorphism group of an acylindrically hyperbolic group G on its space of homogeneous quasimorphisms, and identify its kernel with the subgroup of "strongly commensurating" automorphisms. We deduce that if…

Group Theory · Mathematics 2026-04-21 Ashot Minasyan , Alessandro Sisto , Federico Vigolo

We define and study the class of inner ultrahomogeneous groups, which includes Hall's universal group and the universal locally recursively presentable group. We provide simple criteria for ample generic automorphisms, straight maximality,…

Logic · Mathematics 2024-05-31 Tomasz Rzepecki

If an outer (multilinear) commutator identity holds in a large subgroup of a group, then it holds also in a large characteristic subgroup. Similar assertions are valid for algebras and their ideals or subspaces. Varying the meaning of the…

Group Theory · Mathematics 2010-09-01 Evgenii I. Khukhro , Anton A. Klyachko , Natalia Yu. Makarenko , Yulia B. Melnikova

In this paper, we introduce notions of partitionability and characteristic sets of homogeneous polynomials and give a complete classification of groups faithfully acting on smooth cubic fivefolds. Specifically, we prove that there exist 20…

Algebraic Geometry · Mathematics 2024-08-15 Song Yang , Xun Yu , Zigang Zhu

In this paper we determine automorphism groups of cyclic algebraic curves defined over finite fields of any characteristic.

Algebraic Geometry · Mathematics 2013-01-22 R. Sanjeewa

We investigate some situation in which automorphisms of a group G are uniquely determined by their restrictions to a proper subgroup H. Much of the paper is devoted to studying under which additional hypotheses this property forces G to be…

Group Theory · Mathematics 2007-05-23 Giovanni Cutolo , Chiara Nicotera

We survey recent work on the dynamics of the outer automorphism group of a word hyperbolic group on spaces of (conjugacy classes of) representations ofthe group into a semi-simple Lie group G. All these results are motivated by the fact…

Geometric Topology · Mathematics 2013-06-26 Richard D. Canary

We show that the automorphism group of Drinfeld's half-space over a finite field is the projective linear group of the underlying vector space. The proof of this result uses analytic geometry in the sense of Berkovich over the finite field…

Algebraic Geometry · Mathematics 2019-02-20 Bertrand RÉMY , Amaury Thuillier , Annette Werner

This article proposes an effective criterion for lifting automorphisms along regular coverings of graphs, with the covering transformation group being any finite abelian group.

Combinatorics · Mathematics 2024-02-27 Haimiao Chen

For a finitely generated free group F_n, of rank at least 2, any finite subgroup of Out(F_n) can be realized as a group of automorphisms of a graph with fundamental group F_n. This result, known as Out(F_n) realization, was proved by…

Group Theory · Mathematics 2007-05-23 Matt Clay

We construct a model for the space of automorphisms of a connected p-compact group in terms of the space of automorphisms of its maximal torus normalizer and its root datum. As a consequence we show that any homomorphism to the outer…

Algebraic Topology · Mathematics 2014-11-11 Kasper K. S. Andersen , Jesper Grodal

We show that the outer automorphism groups of graph products of finitely generated abelian groups satisfy the Tits alternative, are residually finite, their so-called Torelli subgroups are finitely generated, and they satisfy a dichotomy…

Group Theory · Mathematics 2021-10-27 Andrew Sale , Tim Susse

We investigate the combinatorial and geometric properties of automorphism groups of universal right-angled Coxeter groups, which are the automorphism groups of free products of copies of Z_2. It is currently an open question as to whether…

Group Theory · Mathematics 2019-10-31 Charles Cunningham