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Due to the increasing discovery and implementation of networks within all disciplines of life, the study of subgraph connectivity has become increasingly important. Motivated by the idea of community (or sub-graph) detection within a…

Combinatorics · Mathematics 2015-05-19 Linda Eroh , Henry Escuardo , Ralucca Gera , Samuel Prahlow , Karl R. B. Schmitt

A \textit{$t$-unit-bar representation} of a graph $G$ is an assignment of sets of at most $t$ horizontal unit-length segments in the plane to the vertices of $G$ so that (1) all of the segments are pairwise nonintersecting, and (2) two…

Combinatorics · Mathematics 2015-08-21 Emily Gaub , Michelle Rose , Paul S. Wenger

Let $S$ be a set of $n$ points in the plane in general position. Two line segments connecting pairs of points of $S$ cross if they have an interior point in common. Two vertex disjoint geometric graphs with vertices in $S$ cross if there…

A graph is $k$-planar if it can be drawn in the plane such that no edge is crossed more than $k$ times. While for $k=1$, optimal $1$-planar graphs, i.e., those with $n$ vertices and exactly $4n-8$ edges, have been completely characterized,…

Computational Geometry · Computer Science 2017-03-21 Michael A. Bekos , Michael Kaufmann , Chrysanthi N. Raftopoulou

In this paper, we prove a number of results about pattern avoidance in graphs with bounded metric dimension or edge metric dimension. We show that the maximum possible number of edges in a graph of diameter $D$ and edge metric dimension $k$…

Combinatorics · Mathematics 2020-03-03 Jesse Geneson

It has long been known that there exist finite connected tetravalent arc-transitive graphs with arbitrarily large vertex-stabilisers. However, beside a well known family of exceptional graphs, related to the lexicographic product of a cycle…

Combinatorics · Mathematics 2010-10-14 Primoz Potocnik , Pablo Spiga , Gabriel Verret

A half-arc-transitive graph is a regular graph that is both vertex- and edge-transitive, but is not arc-transitive. If such a graph has finite valency, then its valency is even, and greater than $2$. In 1970, Bouwer proved that there exists…

Combinatorics · Mathematics 2015-05-12 Marston D. E. Conder , Arjana Žitnik

A graph G is {\xi}-nearly planar if it can be embedded in the sphere so that each of its edges is crossed at most {\xi} times. The family of {\xi}-nearly planar graphs is widely extending the notion of planarity. We introduce an alternative…

Combinatorics · Mathematics 2013-11-04 Alexander Grigoriev , Athanassios Koutsonas , Dimitrios M. Thilikos

Quasi-random graphs can be informally described as graphs whose edge distribution closely resembles that of a truly random graph of the same edge density. Recently, Shapira and Yuster proved the following result on quasi-randomness of…

Combinatorics · Mathematics 2011-05-12 Hao Huang , Choongbum Lee

In the branch of mathematics known as graph theory, graphs are considered as a set of points, called vertices, with connections between these points, called edges. The purpose of this paper is to study mappings between two graphs that have…

Combinatorics · Mathematics 2019-03-19 Jeffrey Beyerl , Cameron Sharpe

Important data mining problems such as nearest-neighbor search and clustering admit theoretical guarantees when restricted to objects embedded in a metric space. Graphs are ubiquitous, and clustering and classification over graphs arise in…

Combinatorics · Mathematics 2018-01-16 Jose Bento , Stratis Ioannidis

We introduce the concept of NIC-planar graphs and present the full characterization of NIC-planar complete k-partite graphs.

Combinatorics · Mathematics 2013-11-11 Xin Zhang

This introduction to graphs and graph algebras provides the optimal bound for the number of all paths of length $k$ in a graph with $N\geq k$ edges and no loops. Our proof relies on a construction of a number of terminating algorithms that…

Rings and Algebras · Mathematics 2019-12-12 Piotr M. Hajac , Mariusz Tobolski

A directed graph is semi-transitive if and only if it is acyclic and for any directed path $u_1\rightarrow u_2\rightarrow \cdots \rightarrow u_t$, $t \geq 2$, either there is no edge from $u_1$ to $u_t$ or all edges $u_i\rightarrow u_j$…

Combinatorics · Mathematics 2021-08-13 Kittitat Iamthong , Sergey Kitaev

We study the impact of forbidding short cycles to the edge density of $k$-planar graphs; a $k$-planar graph is one that can be drawn in the plane with at most $k$ crossings per edge. Specifically, we consider three settings, according to…

We introduce, for every surface {\Sigma}, a two-way connection between FO transductions (first-order logical transformations) of the graphs embeddable in {\Sigma} and a certain variant of fan-crossing drawings of graphs in {\Sigma}. If the…

Computational Geometry · Computer Science 2026-03-13 Petr Hliněný , Jan Jedelský

The 0-1 matrix A contains a 0-1 matrix M if some submatrix of A can be transformed into M by changing some ones to zeroes. If A does not contain M, then A avoids M. Let ex(n,M) be the maximum number of ones in an n x n 0-1 matrix that…

Combinatorics · Mathematics 2014-10-14 Jesse Geneson , Lilly Shen

We present an interactive framework that, given a membership test for a graph class $\mathcal{G}$ and a number $k$, finds and tests unavoidable sets for the class of graphs in $\mathcal{G}$ of path-width at most $k$. We put special emphasis…

Combinatorics · Mathematics 2020-10-19 Oliver Bachtler , Irene Heinrich

Recently, the notion of visibility from the origin has been generalized by viewing lattice points through curved lines of sights, where the family of curves considered are $y=mx^k$, $k\in\mathbb{N}$. In this note, we generalize the notion…

Number Theory · Mathematics 2021-09-20 Sneha Chaubey , Ashish Kumar Pandey

In this paper, we consider the problem of learning an unknown graph via queries on groups of nodes, with the result indicating whether or not at least one edge is present among those nodes. While learning arbitrary graphs with $n$ nodes and…

Information Theory · Computer Science 2020-01-07 Zihan Li , Matthias Fresacher , Jonathan Scarlett