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Packing problems in discrete geometry can be modeled as finding independent sets in infinite graphs where one is interested in independent sets which are as large as possible. For finite graphs one popular way to compute upper bounds for…

Optimization and Control · Mathematics 2021-08-26 David de Laat , Frank Vallentin

The $k$-independence number of a graph $G$ is the maximum size of a set of vertices at pairwise distance greater than $k$. In this paper, for each positive integer $k$, we prove sharp upper bounds for the $k$-independence number in an…

Combinatorics · Mathematics 2020-09-01 Zhenyu Taoqiu , Suil O , Yongtang Shi

In this paper, we obtain two spectral upper bounds for the $k$-independence number of a graph which is is the maximum size of a set of vertices at pairwise distance greater than $k$. We construct graphs that attain equality for our first…

Combinatorics · Mathematics 2016-08-19 Aida Abiad , Sebastian Cioabă , Michael Tait

We introduce a lower bound for the independence number of an arbitrary $k$-uniform hypergraph that only depends on the number of vertices and number of edges of the hypergraph.

Combinatorics · Mathematics 2025-02-18 Marco Aldi , Thor Gabrielsen , Daniele Grandini , Joy Harris , Kyle Kelley

We prove an upper bound for the independence number of a graph in terms of the largest Laplacian eigenvalue, and of a certain induced subgraph. Our bound is a refinement of a well-known Hoffman-type bound.

Combinatorics · Mathematics 2023-11-17 Bogdan Nica

The $k$-independence number of a graph, $\alpha_k(G)$, is the maximum size of a set of vertices at pairwise distance greater than $k$, or alternatively, the independence number of the $k$-th power graph $G^k$. Although it is known that…

Combinatorics · Mathematics 2022-09-07 Aida Abiad , Hidde Koerts

This paper generalizes and unifies the existing spectral bounds on the $k$-independence number of a graph, which is the maximum size of a set of vertices at pairwise distance greater than $k$. The previous bounds known in the literature…

Combinatorics · Mathematics 2018-08-28 A. Abiad , G. Coutinho , M. A. Fiol

For $k\ge 1$, the $k$-independence number $\alpha_k$ of a graph is the maximum number of vertices that are mutually at distance greater than $k$. The well-known inertia and ratio bounds for the (1-)independence number $\alpha(=\alpha_1)$ of…

Combinatorics · Mathematics 2022-01-14 Aida Abiad , Cristina Dalfó , Miquel Àngel Fiol , Sjanne Zeijlemaker

A $k$-independent set in a connected graph is a set of vertices such that any two vertices in the set are at distance greater than $k$ in the graph. The $k$-independence number of a graph, denoted $\alpha_k$, is the size of a largest…

Combinatorics · Mathematics 2023-05-01 Lord C. Kavi , Mike Newman

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

In this paper, we find upper bounds on the open packing and $k$-limited packing numbers with emphasis on the cases $k=1$ and $k=2$. We solve the problem of characterizing all connected graphs on $n$ vertices with $\rho_{o}(G)=n/\delta(G)$…

Combinatorics · Mathematics 2019-08-27 D. A. Mojdeh , B. Samadi , A. Khodkar , H. R. Golmohammadi

We study the existence and the number of $k$-dominating independent sets in certain graph families. While the case $k=1$ namely the case of maximal independent sets - which is originated from Erd\H{o}s and Moser - is widely investigated,…

Combinatorics · Mathematics 2016-12-19 Zoltán Lóránt Nagy

For each uniformity $k \geq 3$, we construct $k$-uniform linear hypergraphs $G$ with arbitrarily large maximum degree $\Delta$ whose independence polynomial $Z_G$ has a root $\lambda$ with $\lvert\lambda\rvert = O\left(\frac{\log…

Combinatorics · Mathematics 2025-07-02 Shengtong Zhang

Let $G$ be a graph of order $n$ and let $k\in\{1,\ldots,n-1\}$. The $k$-token graph $F_k(G)$ of $G$, is the graph whose vertices are the $k$-subsets of $V(G)$, where two vertices are adjacent in $F_k(G)$ whenever their symmetric difference…

Combinatorics · Mathematics 2023-12-01 Hernan de Alba , Walter Carballosa , Jesús Leaños , Luis Manuel Rivera

By Brook's Theorem, every n-vertex graph of maximum degree at most Delta >= 3 and clique number at most Delta is Delta-colorable, and thus it has an independent set of size at least n/Delta. We give an approximate characterization of graphs…

Discrete Mathematics · Computer Science 2019-11-05 Zdenek Dvorak , Bernard Lidicky

The size of a largest independent set of vertices in a given graph $G$ is denoted by $\alpha(G)$ and is called its independence number (or stability number). Given a graph $G$ and an integer $K,$ it is NP-complete to decide whether…

Combinatorics · Mathematics 2017-09-11 Ingo Schiermeyer

The independence number of a hypergraph H is the size of a largest set of vertices containing no edge of H. In this paper, we prove new sharp bounds on the independence number of n-vertex (r+1)-uniform hypergraphs in which every r-element…

Combinatorics · Mathematics 2011-06-17 Alexander Kostochka , Dhruv Mubayi , Jacques Versatraete

A vertex set $S$ is a generalized $k$-independent set if the induced subgraph $G[S]$ contains no tree on $k$ vertices. The generalized $k$-independence number $\alpha_k(G)$ is the maximum size of such a set. For a tree $T$ with $n$…

Combinatorics · Mathematics 2025-09-17 Jing Huang , Jiaxin Tang

We prove a conjecture due to Holroyd and Johnson that an analogue of the Erdos-Ko-Rado theorem holds for k-separated sets. In particular this determines the independence number of the vertex-critical subgraph of the Kneser graph identified…

Combinatorics · Mathematics 2007-05-23 John Talbot

We prove a tight upper bound on the independence polynomial (and total number of independent sets) of cubic graphs of girth at least 5. The bound is achieved by unions of the Heawood graph, the point/line incidence graph of the Fano plane.…

Combinatorics · Mathematics 2018-04-12 Guillem Perarnau , Will Perkins
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