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We develop a categorical framework for studying graphs of groups and their morphisms, with emphasis on pullbacks. More precisely, building on classical work by Serre and Bass, we give an explicit construction of the so-called…

Group Theory · Mathematics 2026-04-15 Jordi Delgado , Marco Linton , Jone Lopez de Gamiz Zearra , Mallika Roy , Pascal Weil

The critical group of a graph is a finite abelian group whose order is the number of spanning forests of the graph. This paper provides three basic structural results on the critical group of a line graph. The first deals with connected…

Combinatorics · Mathematics 2010-06-22 Andrew Berget , Andrew Manion , Molly Maxwell , Aaron Potechin , Victor Reiner

A graph is called a GRR if its automorphism group acts regularly on its vertex-set. Such a graph is necessarily a Cayley graph. Godsil has shown that there are only two infinite families of finite groups that do not admit GRRs : abelian…

Combinatorics · Mathematics 2013-10-03 Joy Morris , Pablo Spiga , Gabriel Verret

We prove the existence of a limiting distribution for the appropriately rescaled diameters of random undirected Cayley graphs of finite nilpotent groups of bounded rank and nilpotency class, thus extending a result of Shapira and Zuck which…

Combinatorics · Mathematics 2020-02-27 Daniel El-Baz , Carlo Pagano

We bound the volume of thick embeddings of finite graphs into the Heisenberg group, as well as the volume of coarse wirings of finite graphs into groups with polynomial growth. This work follows the work of Kolmogorov-Brazdin, Gromov-Guth…

Metric Geometry · Mathematics 2024-10-29 Or Kalifa

We discuss a partial normalisation of a finite graph of finite groups $(\Gamma(-), X)$ which leaves invariant the fundamental group. In conjunction with an easy graph-theoretic result, this provides a flexible and rather useful tool in the…

Group Theory · Mathematics 2018-02-06 Christian Krattenthaler , Thomas W. Müller

T.C. Burness and S.D. Scott \cite{3} classified finite groups $G$ such that the number of prime order subgroups of $G$ is greater than $|G|/2-1$. In this note, we study finite groups $G$ whose subgroup graph contains a vertex of degree…

Group Theory · Mathematics 2025-02-05 Marius Tărnăuceanu

The cogrowth series of a group with respect to a finite generating set is an important combinatorial quantity that seems very difficult to compute exactly, as evidenced by the scarcity of known examples. In this paper, we give a particular…

Combinatorics · Mathematics 2026-05-14 Mudit Aggarwal , Murray Elder , Andrew Rechnitzer

Permutations on a set, endowed with function composition, build a group called a symmetric group. In addition to their algebraic structure, symmetric groups have two metrics that are of particular interest to us here: the Cayley distance…

Mathematical Physics · Physics 2025-09-12 José M. Amigó , Roberto Dale

A new bound for the rank of the intersection of finitely generated subgroups of a free group is given, formulated in topological terms, and very much in the spirit of Stallings. The bound is a contribution to (although unfortunately not a…

Group Theory · Mathematics 2008-12-15 Brent Everitt

The intersection graph $\Delta_G$ of a finite group $G$ is a simple graph with vertices the non-trivial proper subgroups of $G$, and an edge between two vertices if their corresponding subgroups intersect non-trivially. These graphs were…

Group Theory · Mathematics 2024-03-21 Melissa Lee , Kamilla Rekvényi

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

Let $G$ denote a finite abelian group with identity 1 and let $S$ denote an inverse-closed subset of $G \setminus {1}$, which generates $G$ and for which there exists $s \in S$, such that $\la S \setminus \{s,s^{-1}\} \ra \ne G$. In this…

Combinatorics · Mathematics 2012-06-01 Stefko Miklavic , Primoz Sparl

A layerwise search in a split-by-edges tree (as defined by Br{\ae}ndeland, 2015) of agiven graph produces a maximum independent set in exponential time. A depth-first search produces an independent set, which may or may not be a maximum, in…

Data Structures and Algorithms · Computer Science 2015-05-06 Asbjørn Brændeland

We extend the classical Stallings theory (describing subgroups of free groups as automata) to direct products of free and abelian groups: after introducing enriched automata (i.e., automata with extra abelian labels), we obtain an explicit…

Group Theory · Mathematics 2022-06-13 Jordi Delgado , Enric Ventura

We investigate the relationship between finite groups and incidence geometries through their automorphism structures. Building upon classical results on the realizability of groups as automorphism groups of graphs, we develop a general…

Group Theory · Mathematics 2025-12-17 Antonio Díaz Ramos , Rémi Molinier , Antonio Viruel

We generalise the standard constructions of a Cayley graph in terms of a group presentation by allowing some vertices to obey different relators than others. The resulting notion of presentation allows us to represent every vertex…

Combinatorics · Mathematics 2020-07-14 Agelos Georgakopoulos , Matthias Hamann , Alex Wendland

We define a range of new coarse geometric invariants based on various graph-theoretic measures of complexity for finite graphs, including: treewidth, pathwidth, cutwidth and bandwidth. We prove that, for bounded degree graphs, these…

Metric Geometry · Mathematics 2025-08-07 Wanying Huang , David Hume , Samuel J. Kelly , Ryan Lam

Using Cayley graphs and Clifford algebras, we are able to give, for every finitely generated groups, a uniform construction of spectral triples with a generically non-trivial phase for the Dirac operator. Unfortunatly $D_{+}$ is index $0$,…

Operator Algebras · Mathematics 2016-11-10 Sebastien Palcoux

For a transitive infinite connected graph $G$, let $\mu(G)$ be its connective constant. Denote by $\mathbf{\cal G}$ the set of Cayley graphs for finitely generated infinite groups with an infinite-order generator which is independent of…

Probability · Mathematics 2014-10-10 He Song , Kai-Nan Xiang , Song-Chao-Hao Zhu