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We make several observations relating the Lie algebra $\mathfrak{g}_2 \subset \mathfrak{so}(7)$, associative $3$-planes, and $\mathfrak{so}(4)$ subalgebras. Some are likely well-known but not easy to find in the literature, while other…

Differential Geometry · Mathematics 2022-12-08 Max Chemtov , Spiro Karigiannis

We show that the number of conjugacy classes of intersections $A\cap B^g$, for fixed finitely generated subgroups $A, B<F$ of a free group, is bounded above in terms of the ranks of $A$ and $B$; this confirms an intuition of Walter Neumann.…

Group Theory · Mathematics 2021-09-13 Marco Linton

Let G be a group. The intersection graph G(G) of G is an undirected graph without loops and multiple edges defined as follows: the vertex set is the set of all proper nontrivial subgroups of G; and there is an edge between two distinct…

Group Theory · Mathematics 2014-06-13 Ergün Yaraneri

We consider absolutely free nonassociative algebras and, more generally, absolutely free algebras with (maybe infinitely) many multilinear operations. Such algebras are described in terms of labeled reduced planar rooted trees. This allows…

Rings and Algebras · Mathematics 2009-03-25 Vesselin Drensky , Ralf Holtkamp

The aim of this paper is to study the group of isomorphism classes of torsors of finite flat group schemes of rank 2 over a commutative ring $R$. This, in particular, generalises the group of quadratic algebras (free or projective), which…

Algebraic Geometry · Mathematics 2019-02-20 Ilia Pirashvili

Let $G$ be a connected real algebraic group. An unrefinable chain of $G$ is a chain of subgroups $G=G_0>G_1>...>G_t=1$ where each $G_i$ is a maximal connected real subgroup of $G_{i-1}$. The maximal (respectively, minimal) length of such an…

Group Theory · Mathematics 2018-11-16 Damian Sercombe

Given a free group $F_k$ of rank $k\ge 2$ with a fixed set of free generators we associate to any homomorphism $\phi$ from $F_k$ to a group $G$ with a left-invariant semi-norm a generic stretching factor, $\lambda(\phi)$, which is a…

Group Theory · Mathematics 2007-05-23 Vadim Kaimanovich , Ilya Kapovich , Paul Schupp

For a group $G,$ the generating graph of $G,$ denoted by $\Gamma(G).$ We define $Q_n=\langle x,y: x^{2n}=y^4=1, x^n=y^2,y^{-1}xy=x^{-1}\rangle,$ the dicyclic group of order $4n.$ This paper primarily delves into exploring the graph…

Combinatorics · Mathematics 2026-02-23 Kavita Samant , A. Satyanarayana Reddy

There are a variety of ways to associate directed or undirected graphs to a group. It may be interesting to investigate the relations between the structure of these graphs and characterizing certain properties of the group in terms of some…

Group Theory · Mathematics 2017-05-23 A. R. Moghaddamfar , S. Rahbariyan , W. J. Shi

Let $\mathcal{F}$ be a nonempty family of graphs. A graph $G$ is called $\mathcal{F}$-\textit{free} if it contains no graph from $\mathcal{F}$ as a subgraph. For a positive integer $n$, the \emph{planar Tur\'an number} of $\F$, denoted by…

Combinatorics · Mathematics 2023-08-28 Debarun Ghosh , Ervin Győri , Addisu Paulos , Chuanqi Xiao , Oscar Zamora

In [3] is was shown that for any group $G$ whose rank (i.e., minimal number of generators) is at most 3, and any finite index subgroup $H\leq G$ with index $[G:H]\geq rank(G)$, one can always find a left-right transversal of $H$ which…

Group Theory · Mathematics 2019-12-06 Maurice Chiodo , Robert Crumplin , Oscar Donlan , Paweł Piwek

Let $G$ be a finite non-abelian group. The non-commuting graph $\Gamma_G$ of $G$ has the vertex set $G\setminus Z(G)$ and two distinct vertices $x$ and $y$ are adjacent if $xy\ne yx$, where $Z(G)$ is the center of $G$. We prove that the…

Combinatorics · Mathematics 2015-06-16 Yulong Wei , Xuanlong Ma , Kaishun Wang

Let $G$ be a finite group and $f:G \to {\mathbb C}$ be a function. For a non-empty finite subset $Y\subset G$, let $I_Y(f)$ denote the average of $f$ over $Y$. Then, $I_G(f)$ is the average of $f$ over $G$. Using the decomposition of $f$…

Combinatorics · Mathematics 2020-07-23 Hiroki Kajiura , Makoto Matsumoto , Takayuki Okuda

Let $G$ be $2$-generated group. The generating graph of $\Gamma(G)$ is the graph whose vertices are the elements of $G$ and where two vertices $g$ and $h$ are adjacent if $G=\langle g,h\rangle$. This graph encodes the combinatorial…

Group Theory · Mathematics 2020-06-15 Scott Harper , Andrea Lucchini

Poly-free groups are constructed as iterated semidirect products of free groups. The class of poly-free groups includes the classical pure braid groups, fundamental groups of fiber-type hyperplane arrangements, and certain subgroups of the…

Group Theory · Mathematics 2007-05-23 Daniel C. Cohen , F. R. Cohen , Stratos Prassidis

Let G_1 and G_2 be two groups. If a group homomorphism \varphi : G_1 \longrightarrow G_2 maps a \in G_1 into b \in G_2 such that \varphi(a) = b, then we say a degenerates to b and if every element of G_1 degenerates to elements in G_2, then…

Combinatorics · Mathematics 2023-03-14 Rameez Raja

Let $n$ be a positive integer, $\sigma$ be an element of the symmetric group $\mathcal{S}_n$ and let $\sigma$ be a cycle of length $n$. The elements $\alpha ,\beta \in \mathcal{S}_n$ are $\sigma$-equivalent, if there are natural numbers $k$…

Combinatorics · Mathematics 2014-10-31 Krasimir Yordzhev

If $A$ is a unital associative ring and $\ell \geq 2$, then the general linear group $\mathrm{GL}(\ell, A)$ has root subgroups $U_\alpha$ and Weyl elements $n_\alpha$ for $\alpha$ from the root system of type $\mathsf A_{\ell - 1}$.…

Group Theory · Mathematics 2026-05-08 Egor Voronetsky

In this paper, we introduce the concept of $k$-integral graphs. A graph $\Gamma$ is called $k$-integral if the extension degree of the splitting field of the characteristic polynomial of $\Gamma$ over rational field $\mathbb Q$ is equal to…

Combinatorics · Mathematics 2025-08-06 Alireza Abdollahi , Majid Arezoomand , Tao Feng , Shixin Wang

For a finite graph $\Gamma$, let $G(\Gamma)$ be the right-angled Artin group defined by the complement graph of $\Gamma$. We show that, for any linear forest $\Lambda$ and any finite graph $\Gamma$, $G(\Lambda)$ can be embedded into…

Group Theory · Mathematics 2016-12-07 Takuya Katayama