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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

Computing maximum independent sets in graphs is an important problem in computer science. In this paper, we develop an evolutionary algorithm to tackle the problem. The core innovations of the algorithm are very natural combine operations…

Data Structures and Algorithms · Computer Science 2015-02-06 Sebastian Lamm , Peter Sanders , Christian Schulz

A $k$-uniform hypergraph with $n$ vertices is an $(n,k,\ell)$-omitting system if it does not contain two edges whose intersection has size exactly $\ell$. If in addition it does not contain two edges whose intersection has size greater than…

Combinatorics · Mathematics 2021-01-13 Tom Bohman , Xizhi Liu , Dhruv Mubayi

It is known that every proper minor-closed class of graphs has bounded stack-number (a.k.a. book thickness and page number). While this includes notable graph families such as planar graphs and graphs of bounded genus, many other graph…

Computational Geometry · Computer Science 2016-08-24 Vida Dujmović , Fabrizio Frati

The number of independent sets in regular bipartite expander graphs can be efficiently approximated by expressing it as the partition function of a suitable polymer model and truncating its cluster expansion. While this approach has been…

Combinatorics · Mathematics 2024-12-20 Patrick Arras , Frederik Garbe , Felix Joos

Galvin showed that for all fixed $\delta$ and sufficiently large $n$, the $n$-vertex graph with minimum degree $\delta$ that admits the most independent sets is the complete bipartite graph $K_{\delta,n-\delta}$. He conjectured that except…

Combinatorics · Mathematics 2012-04-16 John Engbers , David Galvin

We explore various techniques for counting the number of straight-edge crossing-free graphs that can be embedded on a planar point set. In particular, we derive a lower bound on the ratio of the number of such graphs with $m+1$ edges to the…

Combinatorics · Mathematics 2019-05-24 Siddharth Prasad

Consider a graph on the non-singular matrices over a finite field, in which two distinct non-singular matrices are joined by an edge whenever their sum is singular. We prove an upper bound for the independence number of this graph. As a…

Combinatorics · Mathematics 2024-05-15 Bogdan Nica

A vertex subset $W\subseteq V$ of the graph $G = (V,E)$ is an independent dominating set if every vertex in $V\setminus W$ is adjacent to at least one vertex in $W$ and the vertices of $W$ are pairwise non-adjacent. We enumerate independent…

General Mathematics · Mathematics 2019-10-14 Somayeh Jahari , Saeid Alikhani

Independent sets play a key role into the study of graphs and important problems arising in graph theory reduce to them. We define the monomial ideal of independent sets associated to a finite simple graph and describe its homological and…

Commutative Algebra · Mathematics 2013-07-12 Oana Olteanu

The prime-coprime graph $\Theta(G)$ of a finite group $G$ is the simple graph with vertex set $G$, where two distinct elements are adjacent whenever the greatest common divisor of their orders is either $1$ or a prime. We characterize all…

Group Theory · Mathematics 2026-04-21 Ravi Ranjan , Shubh Narayan Singh , Surbhi Kumari , Shidra Jamil

In this paper we provide an asymptotic expansion for the number of independent sets in a general class of regular, bipartite graphs satisfying some vertex-expansion properties, extending results of Jenssen and Perkins on the hypercube and…

Combinatorics · Mathematics 2025-03-31 Maurício Collares , Joshua Erde , Anna Geisler , Mihyun Kang

We give a very short and simple proof of Zykov's generalization of Tur\'{a}n's theorem, which implies that the number of maximum independent sets of a graph of order $n$ and independence number $\alpha$ with $\alpha<n$ is at most…

Combinatorics · Mathematics 2018-05-08 Elena Mohr , Dieter Rautenbach

The independence number of a tree decomposition is the size of a largest independent set contained in a single bag. The tree-independence number of a graph $G$ is the minimum independence number of a tree decomposition of $G$. As shown…

Data Structures and Algorithms · Computer Science 2026-01-23 Daniel Lokshtanov , Michał Pilipczuk , Paweł Rzążewski

Let $G = (V,E)$ be a graph and $k \ge 0$ an integer. A $k$-independent set $S \subseteq V$ is a set of vertices such that the maximum degree in the graph induced by $S$ is at most $k$. With $\alpha_k(G)$ we denote the maximum cardinality of…

Combinatorics · Mathematics 2012-08-24 Yair Caro , Adriana Hansberg

We improve the best known upper bound on the number of edges in a unit-distance graph on $n$ vertices for each $n\in\{16,\ldots,30\}$. When $n\leq 21$, our bounds match the best known lower bounds, and we fully enumerate the densest…

Combinatorics · Mathematics 2025-02-14 Boris Alexeev , Dustin G. Mixon , Hans Parshall

The following natural problem was raised independently by Erd\H{o}s-Hajnal and Linial-Rabinovich in the late 80's. How large must the independence number $\alpha(G)$ of a graph $G$ be whose every $m$ vertices contain an independent set of…

Combinatorics · Mathematics 2023-01-18 Matija Bucić , Benny Sudakov

Let G be a graph. The independence-domination number is the maximum over all independent sets I in G of the minimal number of vertices needed to dominate I. In this paper we investigate the computational complexity of independence…

Discrete Mathematics · Computer Science 2013-04-25 Wing-Kai Hon , Ton Kloks , Hsiang Hsuan Liu , Sheung-Hung Poon , Yue-Li Wang

This paper studies the problem of upper bounding the number of independent sets in a graph, expressed in terms of its degree distribution. For bipartite regular graphs, Kahn (2001) established a tight upper bound using an…

Combinatorics · Mathematics 2021-04-01 Igal Sason

We develop an experimental algorithm for the exact solving of the maximum independent set problem. The algorithm consecutively finds the maximal independent sets of vertices in an arbitrary undirected graph such that the next such set…

Data Structures and Algorithms · Computer Science 2016-03-02 Anatoly D. Plotnikov