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A graph $G$ is $k$-edge geodetic graph if every edge of $G$ lies in at least one geodesic of length $k$. We studied some basic properties of $k$-edge geodetic graphs. We investigated the $k$ edge-geodeticity of complete bipartite graph…

Combinatorics · Mathematics 2024-08-13 Satyam Guragain , Ravi Srivastava

A graph is said to be edge-transitive if its automorphism group acts transitively on its edges. It is known that edge-transitive graphs are either vertex-transitive or bipartite. In this paper we present a complete classification of all…

Combinatorics · Mathematics 2019-11-13 Heather A. Newman , Hector Miranda , Darren A. Narayan

Let $G = (V,E)$ be a simple finite graph. The corresponding bunkbed graph $G^\pm$ consists of two copies $G^+ = (V^+,E^+),G^- = (V^-,E^-)$ of $G$ and additional edges connecting any two vertices $v_+ \in V_+,v_- \in V_-$ that are the copies…

Probability · Mathematics 2025-03-25 Thomas Richthammer

We study biplane graphs drawn on a finite planar point set $S$ in general position. This is the family of geometric graphs whose vertex set is $S$ and can be decomposed into two plane graphs. We show that two maximal biplane graphs---in the…

Computational Geometry · Computer Science 2017-08-10 Alfredo García , Ferran Hurtado , Matias Korman , Inês Matos , Maria Saumell , Rodrigo I. Silveira , Javier Tejel , Csaba D. Tóth

We prove that a graph has an infinitesimally rigid placement in a non-Euclidean normed plane if and only if it contains a $(2,2)$-tight spanning subgraph. The method uses an inductive construction based on generalised Henneberg moves and…

Metric Geometry · Mathematics 2024-01-18 Sean Dewar

For integer $k\geq2$ and prime power $q$, the algebraic bipartite graph $D(k,q)$ proposed by Lazebnik and Ustimenko (1995) is meaningful not only in extremal graph theory but also in coding theory and cryptography. This graph is…

Combinatorics · Mathematics 2022-07-27 Ming Xu , Xiaoyan Cheng , Yuansheng Tang

A geometric graph is a drawing of a graph in the plane where the vertices are drawn as points in general position and the edges as straight-line segments connecting their endpoints. It is plane if it contains no crossing edges. We study…

Computational Geometry · Computer Science 2025-06-26 Marco Ricci , Jonathan Rollin , André Schulz , Alexandra Weinberger

In this paper we consider the uniformly resolvable decompositions of the complete graph $K_v$, or the complete graph minus a 1-factor as appropriate, into subgraphs such that each resolution class contains only blocks isomorphic to the same…

Combinatorics · Mathematics 2013-12-10 Salvatore Milici , Zsolt Tuza

We present a new model for hybrid planarity that relaxes existing hybrid representations. A graph $G = (V,E)$ is $(k,p)$-planar if $V$ can be partitioned into clusters of size at most $k$ such that $G$ admits a drawing where: (i) each…

Data Structures and Algorithms · Computer Science 2018-09-25 Emilio Di Giacomo , William J. Lenhart , Giuseppe Liotta , Timothy W. Randolph , Alessandra Tappini

Given a set $A$ of $n$ points (vertices) in general position in the plane, the \emph{complete geometric graph} $K_n[A]$ consists of all $\binom{n}{2}$ segments (edges) between the elements of $A$. It is known that the edge set of every…

Combinatorics · Mathematics 2026-04-29 Adrian Dumitrescu , János Pach , Morteza Saghafian , Alex Scott

The nearly complete bipartite graph $G(m,n,k)$ is obtained by removing $k$ independent edges from the complete bipartite graph $K_{m,n}$. In this paper, we prove that for any nearly complete bipartite graph $G(m,n,k)$ with $m, n\geq 3$, and…

Combinatorics · Mathematics 2026-01-13 Shengxiang Lv

We show that for any $2$-local colouring of the edges of the balanced complete bipartite graph $K_{n,n}$, its vertices can be covered with at most~$3$ disjoint monochromatic paths. And, we can cover almost all vertices of any complete or…

Combinatorics · Mathematics 2016-09-13 Richard Lang , Maya Stein

Extending the work of Godsil and others, we investigate the notion of the inverse of a graph (specifically, of bipartite graphs with a unique perfect matching). We provide a concise necessary and sufficient condition for the invertibility…

Combinatorics · Mathematics 2011-08-19 Cam McLeman , Erin McNicholas

We first introduce the class of bipartite absolute retracts with respect to tree obstructions with at most $k$ leaves. Then, using the theory of homomorphism duality, we show that this class of absolute retracts coincides exactly with the…

Combinatorics · Mathematics 2016-09-06 Adam Jaffe

Recently, Milani\v{c} and Trotignon introduced the class of equistarable graphs as graphs without isolated vertices admitting positive weights on the edges such that a subset of edges is of total weight $1$ if and only if it forms a maximal…

Combinatorics · Mathematics 2015-02-24 Endre Boros , Nina Chiarelli , Martin Milanič

We say that a bipartite graph $G(A, B)$ with fixed parts $A$, $B$ is proximinal if there is a semimetric space $(X, d)$ such that $A$ and $B$ are disjoint proximinal subsets of $X$ and all edges $\{a, b\}$ satisfy the equality $d(a, b) =…

Combinatorics · Mathematics 2022-01-24 Karim Chaira , Oleksiy Dovgoshey , Samih Lazaiz

A graph is said to be globally rigid if almost all embeddings of the graph's vertices in the Euclidean plane will define a system of edge-length equations with a unique (up to isometry) solution. In 2007, Jackson, Servatius and Servatius…

Combinatorics · Mathematics 2024-01-29 Sean Dewar

A sparse version of Mantel's Theorem is that, for sufficiently large $p$, with high probability (w.h.p.), every maximum triangle-free subgraph of $G(n,p)$ is bipartite. DeMarco and Kahn proved this for $p>K \sqrt{\log n/n}$ for some…

Combinatorics · Mathematics 2014-11-14 Ran Gu , Xueliang Li , Zhongmei Qin , Yongtang Shi , Kang Yang

In 2009, Kong, Wang, and Lee began work on the problem of finding the edge-balanced index sets of complete bipartite graphs $K_{m,n}$ by solving the cases where $n=1$, $2$, $3$, $4$, and $5$, and also the case where $m=n$. In an article…

Combinatorics · Mathematics 2014-05-08 Hung Hua , Christopher Raridan

We derive a formula for the QE constant of a complete multipartite graph and determine the complete multipartite graphs of non-QE class, namely, those which do not admit quadratic embeddings in a Euclidean space. Moreover, the primary…

Combinatorics · Mathematics 2023-11-09 Nobuaki Obata