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We study set systems formed by neighborhoods in graphs of bounded twin-width. We start by proving that such graphs have linear neighborhood complexity, in analogy to previous results concerning graphs from classes with bounded expansion and…

Logic in Computer Science · Computer Science 2023-04-27 Wojciech Przybyszewski

The bipartition polynomial of a graph is a generalization of many other graph polynomials, including the domination, Ising, matching, independence, cut, and Euler polynomial. We show in this paper that it is also a powerful tool for proving…

Combinatorics · Mathematics 2017-02-14 Seongmin Ok , Peter Tittmann

The paper examines a partial order on bipartite graphs (X1, X2, E) with n vertices, X1UX2={1,2,...,n}. This partial order is a natural partial order of subobjects of an object in a triangular category with bipartite graphs as morphisms.

Discrete Mathematics · Computer Science 2009-06-05 Emil Daniel Schwab

The systematic study of Tur\'an-type extremal problems for edge-ordered graphs was initiated by Gerbner et al. in 2020. Here we characterize connected edge-ordered graphs with linear extremal functions and show that the extremal function of…

Combinatorics · Mathematics 2024-07-12 Gaurav Kucheriya , Gábor Tardos

We extend the closed graph theorem and the open mapping theorem to a context in which a natural duality interchanges their extensions.

Functional Analysis · Mathematics 2019-12-06 R. S. Monahan , P. L. Robinson

This paper deals with dynamical networks for which the relations between node signals are described by proper transfer functions and external signals can influence each of the node signals. In particular, we are interested in…

Optimization and Control · Mathematics 2018-07-24 Henk J. van Waarde , Pietro Tesi , M. Kanat Camlibel

We raise some questions about graph polynomials, highlighting concepts and phenomena that may merit consideration in the development of a general theory. Our questions are mainly of three types: When do graph polynomials have reduction…

Combinatorics · Mathematics 2024-06-25 Graham Farr , Kerri Morgan

We give a combinatorial characterization of graphs whose normalized Laplacian has three distinct eigenvalues. Strongly regular graphs and complete bipartite graphs are examples of such graphs, but we also construct more exotic families of…

Combinatorics · Mathematics 2012-02-15 Edwin R. van Dam , Gholamreza Omidi

A graphical design is a subset of graph vertices such that the weighted averages of certain graph eigenvectors over the design agree with their global averages. We use Gale duality to show that positively weighted graphical designs in…

Combinatorics · Mathematics 2022-07-06 Catherine Babecki , Rekha R. Thomas

We study the existence of perfect matchings in suitably chosen induced subgraphs of random biregular bipartite graphs. We prove a result similar to a classical theorem of Erdos and Renyi about perfect matchings in random bipartite graphs.…

Combinatorics · Mathematics 2013-09-10 Guillem Perarnau , Giorgis Petridis

It is not hard to find many complete bipartite graphs which are not determined by their spectra. We show that the graph obtained by deleting an edge from a complete bipartite graph is determined by its spectrum. We provide some graphs, each…

Combinatorics · Mathematics 2016-01-27 Chia-an Liu , Chih-wen Weng

In this article, we extend several algebraic graph analysis methods to bipartite networks. In various areas of science, engineering and commerce, many types of information can be represented as networks, and thus the discipline of network…

Discrete Mathematics · Computer Science 2015-01-16 Jérôme Kunegis

Interval graphs and interval orders are deeply linked. In fact, edges of an interval graphs represent the incomparability relation of an interval order, and in general, of different interval orders. The question about the conditions under…

Combinatorics · Mathematics 2023-01-03 Marta Fiori-Carones , Alberto Marcone

A tuple (s1,t1,s2,t2) of vertices in a simple undirected graph is 2-linked when there are two vertex-disjoint paths respectively from s1 to t1 and s2 to t2. A graph is 2-linked when all such tuples are 2-linked. We give a new and simple…

Data Structures and Algorithms · Computer Science 2025-08-15 Samuel Humeau , Damien Pous

Graphs derived from groups are a widely studied class of graphs, motivated by their highly symmetric structure. In particular, G-graphs offer an easy and interesting alternative construction of semi-symmetric graphs. After recalling the…

Combinatorics · Mathematics 2016-11-25 David Ellison , Ruxandra Marinescu-Ghemeci , Cerasela Tanasescu

A Graph is called 2-self-centered if its diameter and radius both equal to 2. In this paper, we begin characterizing these graphs by characterizing edge-maximal 2-self-centered graphs via their complements. Then we split characterizing…

Combinatorics · Mathematics 2019-10-29 Mohammad Hadi Shekarriz , Madjid Mirzavaziri , Kamyar Mirzavaziri

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

The periodic discrete Toda equation defined over finite fields has been studied. We obtained the finite graph structures constructed by the network of states where edges denote possible time evolutions. We simplify the graphs by introducing…

Exactly Solvable and Integrable Systems · Physics 2019-06-19 Masataka Kanki , Yuki Takahashi , Tetsuji Tokihiro

In `A survey of two-graphs' \cite{Sei}, J.J. Seidel lays out the connections between simple graphs, two-graphs, equiangular lines and strongly regular graph. It is well known that there is a one-to-one correspondence between regular…

Combinatorics · Mathematics 2017-03-16 Thomas Hoffman , James Solazzo

Graphs are general and powerful data representations which can model complex real-world phenomena, ranging from chemical compounds to social networks; however, effective feature extraction from graphs is not a trivial task, and much work…