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In graph-based applications, a common task is to pinpoint the most important or ``central'' vertex in a (directed or undirected) graph, or rank the vertices of a graph according to their importance. To this end, a plethora of so-called…

Artificial Intelligence · Computer Science 2023-02-28 Andreas Pieris , Jorge Salas

An undirected graph is said to be cordial if there is a friendly (0,1)-labeling of the vertices that induces a friendly (0,1)-labeling of the edges. An undirected graph $G$ is said to be $(2,3)$-orientable if there exists a friendly…

Combinatorics · Mathematics 2024-08-27 LeRoy b. Beasley

This paper is a sequel of our preceding paper (N. Kita: Constructive characterization for signed analogue of critical graphs I: Principal classes of radials and semiradials. arXiv preprint, arXiv:2001.00083, 2019). In the preceding paper,…

Combinatorics · Mathematics 2022-06-03 Nanao Kita

We investigate properties of signed graphs that have few distinct eigenvalues together with a symmetric spectrum. Our main contribution is to determine all signed $(0,2)$-graphs with vertex degree at most $6$ that have precisely two…

Combinatorics · Mathematics 2021-07-27 Gary R. W. Greaves , Zoran Stanić

In this study we consider the problem of triangulated graphs. Precisely we give a necessary and sufficient condition for a graph to be triangulated. This give an alternative characterization of triangulated graphs. Our method is based on…

Combinatorics · Mathematics 2018-11-21 R. Gargouri , H. Najar

A graph is called 1-planar if it can be drawn on the plane so that each edge is crossed by at most one other edge. In this paper, we establish a local property of 1-planar graphs which describes the structure in the neighborhood of small…

Discrete Mathematics · Computer Science 2011-01-04 Xin Zhang , Guizhen Liu , Jian-Liang Wu

This work introduces the concept of \emph{upper-critical graphs}, in a complementary way of the conventional (lower)critical graphs: an element $x$ of a graph $G$ is called \emph{critical} if $\chi(G-x)<\chi(G)$. It is said that $G$ is a…

Combinatorics · Mathematics 2011-04-05 Jose Antonio Martin H

In 2006 Qian [J. Qian, Degree complete graphs; Discrete Mathematics 306 (2006), 533--537] introduced the concept of degree complete graphs for labeled graphs. He also gave a characterization of these graphs in terms of two forbidden…

Combinatorics · Mathematics 2017-06-15 Sebastian Milz

This study is the first part of a detailed study on Type-2 isomorphic circulant graphs having ten parts \cite{v2-1}-\cite{v2-10}. Circulant graphs $C_n(R)$ and $C_n(S)$ are said to be \emph{Adam's isomorphic} if there exist some $a\in…

Combinatorics · Mathematics 2026-05-13 Vilfred Kamalappan

A simple undirected graph is said to be {\em semisymmetric} if it is regular and edge-transitive but not vertex-transitive. Every semisymmetric graph is a bipartite graph with two parts of equal size. It was proved in [{\em J. Combin.…

Combinatorics · Mathematics 2012-06-12 Li Wang , Shaofei Du

The edge betweenness centrality of an edge is loosely defined as the fraction of shortest paths between all pairs of vertices passing through that edge. In this paper, we investigate graphs where the edge betweenness centrality of edges is…

Combinatorics · Mathematics 2017-09-15 Heather A. Newman , Hector Miranda , Rigoberto Florez , Darren A. Narayan

A graph is $k$-chordal if it does not have an induced cycle with length greater than $k$. We call a graph chordal if it is $3$-chordal. Let $G$ be a graph. The distance between the vertices $x$ and $y$, denoted by $d_{G}(x,y)$, is the…

Combinatorics · Mathematics 2022-10-04 James M Shook , Bing Wei

Given an edge-coloring of a graph $G$, we associate to every vertex $v$ of $G$ the set of colors appearing on the edges incident with $v$. The palette index of $G$ is defined as the minimum number of such distinct sets, taken over all…

A subset of vertices in a graph is called a total dominating set if every vertex of the graph is adjacent to at least one vertex of this set. A total dominating set is called minimal if it does not properly contain another total dominating…

Combinatorics · Mathematics 2020-10-07 Selim Bahadır , Tınaz Ekim , Didem Gözüpek

In this paper, our goal is to characterize two graph classes based on the properties of minimal vertex (edge) separators. We first present a structural characterization of graphs in which every minimal vertex separator is a stable set. We…

Discrete Mathematics · Computer Science 2011-03-16 Mrinal Kumar , Gaurav Maheswari , N. Sadagopan

For an edge-colored graph $G$, we call an edge-cut $M$ of $G$ monochromatic if the edges of $M$ are colored with the same color. The graph $G$ is called monochromatic disconnected if any two distinct vertices of $G$ are separated by a…

Combinatorics · Mathematics 2020-09-07 Ping Li , Xueliang Li

In this paper we study the main characteristics of some evaluation codes parameterized by the edges of a bipartite graph with a perfect matching.

Combinatorics · Mathematics 2022-10-04 Manuel Gonzalez Sarabia , Rafael H. Villarreal

A geometric graph is a graph drawn in the plane so that its vertices and edges are represented by points in general position and straight line segments, respectively. A vertex of a geometric graph is called pointed if it lies outside of the…

Combinatorics · Mathematics 2022-08-31 Nikita Chernega , Alexandr Polyanskii , Rinat Sadykov

In \cite{Chan95}, the authors classified the 2-extendable abelian Cayley graphs and posed the problem of characterizing all 2-extendable Cayley graphs. We first show that a connected bipartite Cayley (vertex-transitive) graph is…

Combinatorics · Mathematics 2016-12-12 Qiuli Li , Xing Gao

A bisection of a graph is a bipartition of its vertex set in which the number of vertices in the two parts differ by at most 1, and its size is the number of edges which go across the two parts. In this paper, motivated by several questions…

Combinatorics · Mathematics 2013-05-29 Choongbum Lee , Po-Shen Loh , Benny Sudakov