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Given a graph $G$, the graph $[G]$ obtained by adding, for each pair of vertices of $G$, a unique vertex adjacent to both vertices is called the binding graph of $G$. In this work, we show that the class of binding graphs is…

Combinatorics · Mathematics 2024-08-27 Rui Xue

A connected graph $\Gamma=(V,E)$ of valency at least $3$ is called a basic $2$-arc-transitive graph if its full automorphism group has a subgroup $G$ with the following properties: (i) $G$ acts transitively on the set of $2$-arcs of…

Combinatorics · Mathematics 2022-10-11 Zai Ping Lu , Ruo Yu Song

A graph G is perfect if for every induced subgraph H, the chromatic number of H equals the size of the largest complete subgraph of H, and G is Berge if no induced subgraph of G is an odd cycle of length at least 5 or the complement of one.…

Combinatorics · Mathematics 2007-05-23 Maria Chudnovsky , Neil Robertson , Paul Seymour , Robin Thomas

The girth of a graph is defined as the length of a shortest cycle in the graph. A $(k; g)$-cage is a graph of minimum order among all $k$-regular graphs with girth $g$. A cycle $C$ in a graph $G$ is termed nonseparating if the graph…

Combinatorics · Mathematics 2024-10-10 Xiang-Feng Pan , Jing-Zhong Mao , Hui-Qing Liu

Distance-regular graphs have many beautiful combinatorial properties. Distance-transitive graphs have very strong symmetries, and they are distance-regular, i.e. distance-transitivity implies distance-regularity. In this paper, we give…

Combinatorics · Mathematics 2018-10-23 Hui Zhou , Cheryl Praeger , Michael Giudici , Rongquan Feng , Xingui Fang

We show that there is a collection of subgroups of the mapping class group of a surface such that the associated coset intersection complex is quasi-isometric and homotopy equivalent to the curve complex. Moreover, we prove that these two…

Geometric Topology · Mathematics 2026-03-13 Haoyang He , Eduardo Martínez-Pedroza

Graph dynamical systems (GDSs) can be used to describe a wide range of distributed, nonlinear phenomena. In this paper we characterize cycle equivalence of a class of finite GDSs called sequential dynamical systems SDSs. In general, two…

Dynamical Systems · Mathematics 2009-11-13 Matthew Macauley , Henning S. Mortveit

An alternating cycle in a 2-two-edge-colored graph is a cycle such that any two consecutive edges have different colors. Let $G_1, \ldots, G_k$ be a collection of pairwise vertex disjoint 2-edge-colored graphs. The colored generalized sum…

Combinatorics · Mathematics 2019-10-07 Narda Cordero-Michel , Hortensia Galeana-Sánchez

The Johnson graph $J(n,i)$ is defined to the graph whose vertex set is the set of all $i$-element subsets of $\{1,\ldots,n\}$, and two vertices are joined whenever the cardinality of their intersection is equal to $i-1$. In Ramras and…

Combinatorics · Mathematics 2014-12-17 Ashwin Ganesan

Let $G$ be a transitive permutation group on $\Omega$ with two points $\alpha, \beta\in\Omega$ such that $G_{\alpha}\cap G_{\beta}=1$. The Saxl graph $\Sigma(G)$ of the pair $(G,\Omega)$ is the graph with vertex set $\Omega$, while two…

Group Theory · Mathematics 2026-02-10 Huye Chen , Shaofei Du , Weicong Li

In this paper, we give a lengthy proof of a small result! A graph is bisplit if its vertex set can be partitioned into three stable sets with two of them inducing a complete bipartite graph. We prove that these graphs satisfy the…

Discrete Mathematics · Computer Science 2023-06-22 Laurent Beaudou , Giacomo Kahn , Matthieu Rosenfeld

Let $G$ be a finite group and let $S$ be an inverse-closed subset of $G$ not containing the identity. The Cayley graph $\mathrm{Cay}(G,S)$ has vertex set $G$, where two vertices $x$ and $y$ are adjacent if and only if $x^{-1}y \in S$.…

Combinatorics · Mathematics 2026-01-06 Amitayu Banerjee

The Johnson graph $J(n, i)$ is defined as the graph whose vertex set is the set of all $i$-element subsets of $\{1, . . ., n \}$, and two vertices are adjacent whenever the cardinality of their intersection is equal to $i$-1. In Ramras and…

Combinatorics · Mathematics 2017-10-17 S. Morteza Mirafzal

A permutation graph is a cubic graph admitting a 1-factor M whose complement consists of two chordless cycles. Extending results of Ellingham and of Goldwasser and Zhang, we prove that if e is an edge of M such that every 4-cycle containing…

Combinatorics · Mathematics 2012-04-11 Tomáš Kaiser , Jean-Sébastien Sereni , Zelealem Yilma

A $biased\ graph$ is a pair $(G,\mathcal{B})$, where $G$ is a graph and $\mathcal{B}$ is a collection of `balanced' circuits of $G$ such that no $\Theta$-subgraph of $G$ contains precisely two balanced circuits. We prove a Ramsey-type…

Combinatorics · Mathematics 2018-03-28 Peter Nelson , Sophia Park

In order to complete (and generalize) results of Gardiner and Praeger on 4-valent symmetric graphs (European J. Combin, 15 (1994)) we apply the method of lifting automorphisms in the context of elementary-abelian covering projections. In…

Combinatorics · Mathematics 2017-08-01 Boštjan Kuzman , Aleksander Malnič , Primož Potočnik

In this paper, we are motivated by the conjectures proposed by C.~Bender \textit{et al.}, \cite{C} in 2024. We have settled the first two conjectures negatively by providing a counter example in \cite{KTJ}, whereas in this paper, we prove…

Combinatorics · Mathematics 2026-04-20 Anagha Khiste , Ganesh Tarte , Vinayak Joshi

Circular arc graphs are graphs whose vertices can be represented as arcs on a circle such that any two vertices are adjacent if and only if their corresponding arcs intersect. Proper circular arc graphs are graphs which have a circular arc…

Combinatorics · Mathematics 2007-05-23 Naveen Belkale , L. Sunil Chandran

The graph reconstruction conjecture asserts that every finite simple graph on at least three vertices can be reconstructed up to isomorphism from its deck - the collection of its vertex-deleted subgraphs. Kocay's Lemma is an important tool…

Combinatorics · Mathematics 2014-09-09 Igor C. Oliveira , Bhalchandra D. Thatte

When dealing with symmetry properties of mathematical objects, one of the fundamental questions is to determine their full automorphism group. In this paper this question is considered in the context of even/odd permutations dichotomy. More…

Combinatorics · Mathematics 2016-08-30 Klavdija Kutnar , Dragan Marusic