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In this paper we consider Contact graphs of Paths on a Grid (CPG graphs), i.e. graphs for which there exists a family of interiorly disjoint paths on a grid in one-to-one correspondence with their vertex set such that two vertices are…

Computational Geometry · Computer Science 2018-09-07 Zakir Deniz , Esther Galby , Andrea Munaro , Bernard Ries

A graph is $\textit{cubelike}$ if it is a Cayley graph for some elementary abelian $2$-group $\mathbb{Z}_2^n$. The core of a graph is its smallest subgraph to which it admits a homomorphism. More than ten years ago, Ne\v{s}et\v{r}il and…

Combinatorics · Mathematics 2018-08-08 Laura Mančinska , Irene Pivotto , David E. Roberson , Gordon Royle

Minimal prime graphs (MPGs) are a special class of prime graphs (also known as Gruenberg-Kegel graphs) associated with finite solvable groups. A graph is an MPG if it has at least two vertices, is connected, its complement is triangle-free…

Combinatorics · Mathematics 2026-02-03 Micah Dorton , Thomas Michael Keller , Ryan Tang , Justin Yu

We study the Universal Difference Property (UDP) introduced by Alt{\i}nok, Anders, Arreola, Asencio, Ireland, Sar{\i}o\u{g}lan, and Smith, focusing on the relationship between the structural properties of a graph and UDP. We present…

Combinatorics · Mathematics 2026-01-21 Katie Anders , Able Martinez , Patrick McHugh , Jenna Rogers , Remi Salinas Schmeis

An {\it overlap representation} of a graph $G$ assigns sets to vertices so that vertices are adjacent if and only if their assigned sets intersect with neither containing the other. The {\it overlap number} $\ol(G)$ (introduced by Rosgen)…

A complex unit gain graph is a triple $\varphi=(G, \mathbb{T}, \varphi)$ (or $G^{\varphi}$ for short) consisting of a simple graph $G$, as the underlying graph of $G^{\varphi}$, the set of unit complex numbers $\mathbb{T}={z\in \mathbb{C}:…

Combinatorics · Mathematics 2021-08-04 Yong Lu , Qi Wu

A median graph is a connected graph, such that for any three vertices $u,v,w$ there is exactly one vertex $x$ that lies simultaneously on a shortest $(u,v)$-path, a shortest $(v,w)$-path and a shortest $(w,u)$-path. Examples of median…

Combinatorics · Mathematics 2016-01-29 Konstantinos Stavropoulos

The algebraic degree $Deg(G)$ of a graph $G$ is the dimension of the splitting field of the adjacency polynomial of $G$ over the field $\mathbb{Q}$. It can be shown that for every positive integer $d$, there exists a circulant graph with…

Combinatorics · Mathematics 2025-07-24 Sauvik Poddar , Angsuman Das

Let $G$ be a connected graph and let $F$ be a connected subgraph of $G$ with a given structure. We consider that the centrality of a vertex $i$ of $G$ is determined by the centrality of other vertices in all subgraphs contain $i$ and…

Combinatorics · Mathematics 2024-11-20 Qingying Zhang , Lizhu Sun , Changjiang Bu

For a graph property $\mathcal{P}$ and a common vertex set $V = \{1, 2, \ldots, n\}$, a family of graphs on $V$ is \emph{$\mathcal{P}$-intersecting} iff $G \cap H$ satisfies $\mathcal{P}$ for all $G,H$ in the family. Addressing a question…

Combinatorics · Mathematics 2019-01-08 Aaron Berger , Ross Berkowitz , Pat Devlin , Michael Doppelt , Sonali Durham , Tessa Murthy , Harish Vemuri

In a representation of a graph $G$ as an edge intersection graph of paths on a grid (EPG) every vertex of $G$ is represented by a path on a grid and two paths share a grid edge iff the corresponding vertices are adjacent. In a monotonic EPG…

Combinatorics · Mathematics 2023-01-02 Eranda Cela , Elisabeth Gaar

A graph is Berge if it has no induced odd cycle on at least 5 vertices and no complement of induced odd cycle on at least 5 vertices. A graph is perfect if the chromatic number equals the maximum clique number for every induced subgraph.…

Combinatorics · Mathematics 2013-09-10 Michel Burlet , Frédéric Maffray , Nicolas Trotignon

A path in an edge-colored graph is called a proper path if no two adjacent edges of the path are colored with one same color. An edge-colored graph is called $k$-proper connected if any two vertices of the graph are connected by $k$…

Combinatorics · Mathematics 2015-07-13 Fei Huang , Xueliang Li , Shujing Wang

The quadratic embedding constant (QEC) of a graph $G$ is a new numeric invariant, which is defined in terms of the distance matrix and is denoted by $\mathrm{QEC}(G)$. By observing graph structure of the maximal cliques (clique graph), we…

Combinatorics · Mathematics 2024-05-08 Edy Tri Baskoro , Nobuaki Obata

A set S is independent in a graph G if no two vertices from S are adjacent. By core(G) we mean the intersection of all maximum independent sets. The independence number alpha(G) is the cardinality of a maximum independent set, while mu(G)…

Discrete Mathematics · Computer Science 2011-02-24 Vadim E. Levit , Eugen Mandrescu

In a graph, we assign distinct integers to the vertices, and take the sum of two integers if they are on two adjacent vertices. The minimum possible number of different sums is the \emph{sum index} of this graph. In this paper, we present…

Combinatorics · Mathematics 2025-07-29 Dheer Noal Desai , Runze Wang

The enhanced power graph $\mathcal{P}_e(G)$ of a group $G$ is a graph with vertex set $G$ and two vertices are adjacent if they belong to the same cyclic subgroup. In this paper, we consider the minimum degree, independence number and…

Group Theory · Mathematics 2020-01-27 Ramesh Prasad Panda , Sandeep dalal , Jitender Kumar

Graph Convolutional Networks (GCNs) have achieved impressive performance in a wide variety of areas, attracting considerable attention. The core step of GCNs is the information-passing framework that considers all information from neighbors…

Machine Learning · Computer Science 2022-02-17 Feng Xia , Lei Wang , Tao Tang , Xin Chen , Xiangjie Kong , Giles Oatley , Irwin King

The edge clique cover number $ecc(G)$ of a graph $G$ is the size of the smallest set of complete subgraphs whose union covers all edges of $G$. It has been conjectured that all the simple graphs with independence number two satisfy…

Combinatorics · Mathematics 2021-12-09 Frank Ramamonjisoa

A 1-factor of a hypergraph $G=(X,W)$ is a set of hyperedges such that every vertex of $G$ is incident to exactly one hyperedge from the set. A 1-factorization is a partition of all hyperedges of $G$ into disjoint 1-factors. The adjacency…

Combinatorics · Mathematics 2016-12-06 Anna Taranenko