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Graphlet analysis is an approach to network analysis that is particularly popular in bioinformatics. We show how to set up a system of linear equations that relate the orbit counts and can be used in an algorithm that is significantly…

Data Structures and Algorithms · Computer Science 2017-04-12 Tomaž Hočevar , Janez Demšar

We define the Euler number of a bipartite graph on $n$ vertices to be the number of labelings of the vertices with $1,2,...,n$ such that the vertices alternate in being local maxima and local minima. We reformulate the problem of computing…

Combinatorics · Mathematics 2010-02-22 Richard Ehrenborg , Yossi Farjoun

In this article, we introduce the notion of a wedge of graphs and provide detailed computations for the independence complex of a wedge of path and cycle graphs. In particular, we show that these complexes are either contractible or wedges…

Combinatorics · Mathematics 2023-03-20 Navnath Daundkar , Saikat Panja , Sachchidanand Prasad

Suppose a finite, unweighted, combinatorial graph $G = (V,E)$ is the union of several (degree-)regular graphs which are then additionally connected with a few additional edges. $G$ will then have only a small number of vertices $v \in V$…

Combinatorics · Mathematics 2023-10-25 Tony Zeng

An odd independent set $S$ in a graph $G=(V,E)$ is an independent set of vertices such that, for every vertex $v \in V \setminus S$, either $N(v) \cap S = \emptyset$ or $|N(v) \cap S| \equiv 1$ (mod 2), where $N(v)$ stands for the open…

Combinatorics · Mathematics 2025-10-03 Yair Caro , Mirko Petruševski , Riste Škrekovski , Zsolt Tuza

Subgraph enumeration problems ask to output all subgraphs of an input graph that belongs to the specified graph class or satisfy the given constraint. These problems have been widely studied in theoretical computer science. As far, many…

Data Structures and Algorithms · Computer Science 2018-07-03 Kunihiro Wasa , Takeaki Uno

A set of independence statements may define the independence structure of interest in a family of joint probability distributions. This structure is often captured by a graph that consists of nodes representing the random variables and of…

Methodology · Statistics 2011-07-15 Nanny Wermuth

Given an edge-coloring of a graph, the palette of a vertex is defined as the set of colors of the edges which are incident with it. We define the palette index of a graph as the minimum number of distinct palettes, taken over all…

Combinatorics · Mathematics 2021-07-09 Davide Mattiolo , Giuseppe Mazzuoccolo , Gloria Tabarelli

We consider the number of independent sets in hypergraphs, which allows us to define the independence density of countable hypergraphs. Hypergraph independence densities include a broad family of densities over graphs and relational…

Combinatorics · Mathematics 2013-08-14 Anthony Bonato , Jason Brown , Dieter Mitsche , Pawel Pralat

A mixed graph is obtained by orienting some edges of a simple graph. The positive inertia index of a mixed graph is defined as the number of positive eigenvalues of its Hermitian adjacency matrix, including multiplicities. This matrix was…

Combinatorics · Mathematics 2021-02-23 Xiaocong He , Lihua Feng

Graph generation with Machine Learning is an open problem with applications in various research fields. In this work, we propose to cast the generative process of a graph into a sequential one, relying on a node ordering procedure. We use…

Machine Learning · Statistics 2020-04-24 Davide Bacciu , Alessio Micheli , Marco Podda

An independent transversal (IT) in a graph with a given vertex partition is an independent set consisting of one vertex in each partition class. Several sufficient conditions are known for the existence of an IT in a given graph with a…

Data Structures and Algorithms · Computer Science 2023-10-13 Alessandra Graf , David G. Harris , Penny Haxell

We characterise the structure of those graphs of a given order which maximise the number of connected induced subgraphs for seven different graph classes, each with other prescribed parameters like minimum degree, independence number,…

Combinatorics · Mathematics 2023-03-06 Audace A. V. Dossou-Olory

A bihole in a bipartite graph $G$ with partite sets $A$ and $B$ is an independent set $I$ in $G$ with $|I\cap A|=|I\cap B|$. We prove lower bounds on the largest order of biholes in balanced bipartite graphs subject to conditions involving…

Combinatorics · Mathematics 2020-04-13 Stefan Ehard , Elena Mohr , Dieter Rautenbach

A theorem of Ding, Oporowski, Oxley, and Vertigan implies that any sufficiently large twin-free graph contains a large matching, a co-matching, or a half-graph as a semi-induced subgraph. The sizes of these unavoidable patterns are measured…

Computational Complexity · Computer Science 2026-02-10 Jan Dreier , Nikolas Mählmann , Sebastian Siebertz

We study the number of connected graphs with $n$ vertices that cannot be written as the cartesian product of two graphs with fewer vertices. We give an upper bound which implies that for large $n$ almost all graphs are both connected and…

Combinatorics · Mathematics 2024-02-23 Marco Aldi

We show that there are polynomial-time algorithms to compute maximum independent sets in the categorical products of two cographs and two splitgraphs. The ultimate categorical independence ratio of a graph G is defined as lim_{k --> infty}…

Discrete Mathematics · Computer Science 2013-06-10 Wing-Kai Hon , Ton Kloks , Hsiang-Hsuan Liu , Sheung-Hung Poon , Yue-Li Wang

The independence equivalence class of a graph $G$ is the set of graphs that have the same independence polynomial as $G$. A graph whose independence equivalence class contains only itself, up to isomorphism, is independence unique. Beaton,…

Combinatorics · Mathematics 2022-09-14 Boon Leong Ng

We find the asymptotic number of connected graphs with $k$ vertices and $k-1+l$ edges when $k,l$ approach infinity, reproving a result of Bender, Canfield and McKay. We use the {\em probabilistic method}, analyzing breadth-first search on…

Combinatorics · Mathematics 2007-05-23 Remco van der Hofstad , Joel Spencer

The Havel-Hakimi algorithm iteratively reduces the degree sequence of a graph to a list of zeroes. As shown by Favaron, Mah\'eo, and Sacl\'e, the number of zeroes produced, known as the residue, is a lower bound on the independence number…

Combinatorics · Mathematics 2019-09-17 Michael D. Barrus , Grant Molnar