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We determine which simple algebraic groups of type $^3D_4$ over arbitrary fields of characteristic different from 2 admit outer automorphisms of order 3, and classify these automorphisms up to conjugation. The criterion is formulated in…

Group Theory · Mathematics 2014-09-08 Max-Albert Knus , Jean-Pierre Tignol

We give a condition on the defining graph of a right-angled Artin group which implies its automorphism group is virtually indicable, that is, it has a finite-index subgroup that admits a homomorphism onto $\Z$. We use this as part of a…

Group Theory · Mathematics 2020-11-10 Andrew Sale

We calculate the higher topological complexity TC$_s$ for the complements of reflection arrangements, in other words for the pure Artin type groups of all finite complex reflection groups. In order to do that we introduce a simple…

Algebraic Topology · Mathematics 2014-11-10 Sergey Yuzvinsky

This text brings to an end the classification of non-reduced parabolic subgroups in positive characteristic, especially two and three: they are all obtained as intersections of parabolics having maximal reduced part. We prove this result…

Algebraic Geometry · Mathematics 2023-12-04 Matilde Maccan

Let $N$ be a closed nonorientable surface with or without marked points. In this paper we prove that, for every finite full subgraph $\Gamma$ of $\mathcal{C}^{\mathrm{two}}(N)$, the right-angled Artin group on $\Gamma$ can be embedded in…

Geometric Topology · Mathematics 2023-08-25 Takuya Katayama , Erika Kuno

We study the outer automorphism group of a right-angled Artin group $A_\Gamma$ with finite defining graph $\Gamma$. We construct a subnormal series for $Out(A_\Gamma)$ such that each consecutive quotient is either finite, free-abelian,…

Group Theory · Mathematics 2019-04-24 Matthew B. Day , Richard D. Wade

In this article, we prove that embeddings of right-angled Artin group $A_1$ on the complement of a linear forest into another right-angled Artin group $A_2$ can be reduced to full embeddings of the defining graph of $A_1$ into the extension…

Group Theory · Mathematics 2017-10-10 Takuya Katayama

An automorphism $\alpha$ of a group $G$ is normal if it fixes every normal subgroup of $G$ setwise. We give an algebraic description of normal automorphisms of relatively hyperbolic groups. In particular, we prove that for any relatively…

Group Theory · Mathematics 2011-02-15 A. Minasyan , D. Osin

We prove that certain sequences of Artin monoids containing the braid monoid as a submonoid satisfy homological stability. When the $K(\pi,1)$ conjecture holds for the associated family of Artin groups this establishes homological stability…

Algebraic Topology · Mathematics 2020-05-06 Rachael Boyd

Based on a normal form for braid group elements suggested by Dehornoy, we prove several representations of braid groups by automorphisms of a free group to be faithful. This includes a simple proof of the standard Artin's representation…

Group Theory · Mathematics 2007-05-23 Vladimir Shpilrain

We generalise the techniques of arXiv:0908.1963 to describe derived deformations in simplicial categories. This allows us to consider deformation problems with higher automorphisms, such as chain complexes (which have homotopies) and stacks…

Algebraic Geometry · Mathematics 2015-02-03 J. P. Pridham

The structure of a certain subgroup $S$ of the automorphism group of a partially commutative group (RAAG) $G$ is described in detail: namely the subgroup generated by inversions and elementary transvections. We define admissible subsets of…

Group Theory · Mathematics 2017-06-30 Andrew J. Duncan , Vladimir N. Remeslennikov

While finite type Artin groups and right-angled Artin groups are well-understood, little is known about more general Artin groups. In this paper we use the action of an infinite type Artin group $A_\Gamma$ on a CAT(0) cube complex to prove…

Group Theory · Mathematics 2018-06-04 Ruth Charney , Rose Morris-Wright

We give an explicit formula for the cohomology of a right angled Artin group with group ring coefficients in terms of the cohomology of its defining flag complex.

Geometric Topology · Mathematics 2007-05-23 Craig Jensen , John Meier

Based on a thorough theory of the Artin transfer homomorphism \(T_{G,H}:\,G\to H/H^\prime\) from a group \(G\) to the abelianization \(H/H^\prime\) of a subgroup \(H\le G\) of finite index \(n=(G:H)\), and its connection with the…

Group Theory · Mathematics 2015-11-25 Daniel C. Mayer

Let $\ell$ be a prime divisor of the order of a finite unitary reflection group. We classify up to conjugacy the parabolic and reflection subgroups that are minimal with respect to inclusion, subject to containing an $\ell$-Sylow subgroup.…

Group Theory · Mathematics 2020-05-12 Kane Douglas Townsend

Suppose that $(T,\star)$ is a groupoid with a left identity such that each element $a\in T$ has a left inverse. Then $T$ is called a \textit{gyrogroup} if and only if $(i)$ there exists a function $gyr:T\times T\longrightarrow Aut(T)$ such…

Group Theory · Mathematics 2021-06-08 S. Mahdavi , A. R. Ashrafi , M. A. Salahshour

We determine a classification of the endomorphisms of the Artin group of affine type $\tilde A_n$ for $n\ge 4$.

Group Theory · Mathematics 2026-04-16 Luis Paris , Ignat Soroko

The result of this paper is the determination of the cohomology of Artin groups of type A_n, B_n and \tilde{A}_{n} with non-trivial local coefficients. The main result is an explicit computation of the cohomology of the Artin group of type…

Algebraic Topology · Mathematics 2007-05-23 Filippo Callegaro , Davide Moroni , Mario Salvetti

We investigate criteria ensuring that a one-relator group $G$ contains a right-angled Artin subgroup $A(\Gamma)$, corresponding to a finite graph $\Gamma$. In particular, we prove that if $\Gamma$ is a forest with at least one edge and the…

Group Theory · Mathematics 2025-08-01 Ashot Minasyan , Motiejus Valiunas