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For a subgroup $H$ of a finite group $G$, the Frobenius graph $\Gamma(G, H)$ records the constituents of the restrictions to $H$ of the irreducible characters of $G$. We investigate when this graph has diameter 3.

Group Theory · Mathematics 2024-07-12 Thomas Breuer , László Héthelyi , Erzsébet Horváth , Burkhard Külshammer

We investigate prime character degree graphs of solvable groups. In particular, we consider a family of graphs $\Gamma_{k,t}$ constructed by adjoining edges between two complete graphs in a one-to-one fashion. In this paper we determine…

Group Theory · Mathematics 2018-03-15 Mark W. Bissler , Jacob Laubacher

A set of vertices $S$ \emph{resolves} a connected graph $G$ if every vertex is uniquely determined by its vector of distances to the vertices in $S$. The \emph{metric dimension} of $G$ is the minimum cardinality of a resolving set of $G$.…

Combinatorics · Mathematics 2012-05-21 Carmen Hernando , Merce Mora , Ignacio M. Pelayo , Carlos Seara , David R. Wood

For a finite group $G$, let $\Delta(G)$ denote the character graph built on the set of degrees of the irreducible complex characters of $G$. In this paper, we determine the structure of all finite groups $G$ with $K_4$-free character graph…

Group Theory · Mathematics 2019-09-04 Mahdi Ebrahimi

We study here the graphs with seven vertices in an effort to classify which of them appear as the prime character degree graphs of finite solvable groups. This classification is complete for the disconnected graphs. Of the 853…

Group Theory · Mathematics 2023-08-03 Jacob Laubacher , Mark Medwid , Dylan Schuster

Let $G$ be a finite group and let $\rm{Irr}(G)$ be the set of all irreducible complex characters of $G$. Let $\rm{cd}(G)$ be the set of all character degrees of $G$ and denote by $\rho(G)$ the set of primes which divide some character…

Group Theory · Mathematics 2020-06-30 Mahdi Ebrahimi

Let \pi(G) denote the set of prime divisors of the order of a finite group G. The prime graph of G is the graph with vertex set \pi(G) with edges {p,q} if and only if there exists an element of order pq in G. In this paper, we prove that a…

Group Theory · Mathematics 2013-05-13 Alexander Gruber , Thomas Keller , Mark Lewis , Keeley Naughton , Benjamin Strasser

Given a finite group $G$, the difference graph of $G$, denoted by $\mathcal{D}(G)$, is the difference of the enhanced power graph of $G$ and the power graph of $G$, with all isolated vertices removed. This paper mainly studies the…

Group Theory · Mathematics 2026-01-06 Xuanlong Ma , Samir Zahirović , Katarina Žigerović

Let $G$ be a finite group and $\mathrm{Irr}(G)$ be the set of all complex irreducible characters of $G$. The character-graph $\Delta(G)$ associated to $G$, is a graph whose vertex set is the set of primes which divide the degrees of some…

Group Theory · Mathematics 2021-09-27 Mahdi Ebrahimi , Maryam Khatami , Zohreh Mirzaei

To any finite group $G$, we may associate a graph whose vertices are the elements of $G$ and where two distinct vertices $x$ and $y$ are adjacent if and only if the order of the subgroup $\langle x, y\rangle$ is divisible by at least 3…

Group Theory · Mathematics 2023-09-12 Karmele Garatea-Zaballa , Andrea Lucchini

we obtain a necessary condition for the character degree graph with all of its vertices are odd degree of a finite solvable group G.

Group Theory · Mathematics 2023-05-23 G. Sivanesan , C. Selvaraj

We prove that if the average of the degrees of the irreducible characters of a finite group $G$ is less than 16/5, then $G$ is solvable. This solves a conjecture of I.M. Isaacs, M. Loukaki, and the first author. We discuss related…

Group Theory · Mathematics 2013-12-06 Alexander Moretó , Hung Ngoc Nguyen

The commensurability index between two subgroups $A, B$ of a group $G$ is $[A : A \cap B] [B : A\cap B]$. This gives a notion of distance amongst finite-index subgroups of $G$, which is encoded in the p-local commensurability graphs of $G$.…

Group Theory · Mathematics 2015-12-07 Khalid Bou-Rabee , Chen Shi

Let $G$ be a finite group, and let $\Delta(G)$ be the prime graph built on the set of conjugacy class sizes of $G$: this is the simple undirected graph whose vertices are the prime numbers dividing some conjugacy class size of $G$, two…

Group Theory · Mathematics 2019-12-23 Silvio Dolfi , Emanuele Pacifici , Lucía Sanus , Víctor Sotomayor

For a finite group $G$, let $\Delta(G)$ denote the character graph built on the set of degrees of the irreducible complex characters of $G$. Akhlaghi and Tong-Viet in \cite{[AT]} conjectured that if for some positive integer $n$,…

Group Theory · Mathematics 2020-02-18 Mahdi Ebrahimi

Let $G$ be a finite solvable group with disconnected character degree graph $\Delta(G)$. Under these conditions, it follows from a result of P\'alfy that $\Delta(G)$ consists of two connected components. Another result of P\'alfy's gives an…

Combinatorics · Mathematics 2025-04-03 Mark L. Lewis , Andrew Summers

Let $G$ be a finite group. The bipartite divisor graph for the set of irreducible complex character degrees is the undirected graph with vertex set consisting of the prime numbers dividing some character degree and of the non-identity…

Group Theory · Mathematics 2019-06-21 Roghayeh Hafezieh , Pablo Spiga

If $G$ is a solvable group, we take $\Delta (G)$ to be the character degree graph for $G$ with primes as vertices. We prove that if $\Delta (G)$ is a square, then $G$ must be a direct product.

Group Theory · Mathematics 2014-11-13 Mark L. Lewis , Qingyun Meng

The nilpotent graph of a group $G$ is the simple and undirected graph whose vertices are the elements of $G$ and two distinct vertices are adjacent if they generate a nilpotent subgroup of $G$. Here we discuss some topological properties of…

Group Theory · Mathematics 2025-02-11 Costantino Delizia , Michele Gaeta , Mark L. Lewis , Carmine Monetta

The degree diameter problem asks for the maximum possible number of vertices in a graph of maximum degree $\Delta$ and diameter $D$. In this paper, we focus on planar graphs of diameter $3$. Fellows, Hell and Seyffarth (1995) proved that…

Combinatorics · Mathematics 2025-07-28 Antoine Dailly , Sasha Darmon , Ugo Giocanti , Claire Hilaire , Petru Valicov