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We study the class of independence complexes of claw-free graphs. The main theorem give good bounds on the connectivity of these complexes, given bounds for a few subcomplexes of the same class. Two applications are presented. Firstly, we…

Combinatorics · Mathematics 2007-05-23 Alexander Engström

An independent set in a graph is a set of pairwise non-adjacent vertices. The independence number $\alpha{(G)}$ is the size of a maximum independent set in the graph $G$. The independence polynomial of a graph is the generating function for…

Discrete Mathematics · Computer Science 2022-03-08 Ron Yosef , Matan Mizrachi , Ohr Kadrawi

In this paper, we study the independence polynomial $P_G(x)$ of a finite simple graph $G$, with emphasis on the evaluation at $x=-1$, symmetry, and its connection with the $h$-polynomial of the edge ideal of $G$. For big star graphs, we…

Combinatorics · Mathematics 2026-03-18 Takayuki Hibi , Selvi Kara , Dalena Vien

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 investigate Feynman graphs and their Feynman rules from the viewpoint of graph complexes. We focus on graph homology and on the appearance of cubical complexes when either reducing internal edges or when removing them by putting them on…

High Energy Physics - Theory · Physics 2023-02-27 Marko Berghoff , Dirk Kreimer

We study the zero sets of the independence polynomial on recursive sequences of graphs. We prove that for a maximally independent starting graph and a stable and expanding recursion algorithm, the zeros of the independence polynomial are…

Dynamical Systems · Mathematics 2024-11-25 Mikhail Hlushchanka , Han Peters

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

The independence gap of a graph was introduced by Ekim et al. (2018) as a measure of how far a graph is from being well-covered. It is defined as the difference between the maximum and minimum size of a maximal independent set. We…

Combinatorics · Mathematics 2018-12-14 Tınaz Ekim , Didem Gözüpek , Ademir Hujdurović , Martin Milanič

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

Various simplicial complexes can be associated with a graph. Box complexes form an important families of such simplicial complexes and are especially useful for providing lower bounds on the chromatic number of the graph via some of their…

Combinatorics · Mathematics 2024-01-05 Hamid Reza Daneshpajouh , Frédéric Meunier

Let $G=(V,E)$ be a graph and $n$ a positive integer. Let $I_n(G)$ be the abstract simplicial complex whose simplices are the subsets of $V$ that do not contain an independent set of size $n$ in $G$. We study the collapsibility numbers of…

Combinatorics · Mathematics 2024-10-15 Minki Kim , Alan Lew

We provide lower bounds on the connectivity of the independence complexes of hypergraphs. Additionally, we compute the homotopy types of the independence complexes of $d$-uniform properly-connected triangulated hypergraphs.

Combinatorics · Mathematics 2024-11-18 Demet Taylan

Nanoparticles with "sticky patches" have long been proposed as building blocks for the self-assembly of complex structures. The synthetic realizability of such patchy particles, however, greatly lags behind predictions of patterns they…

Soft Condensed Matter · Physics 2013-10-03 Michael Grünwald , Phillip L. Geissler

A locally flatly embedded $2$-sphere in a compact $4$-manifold $X$ is called a spine if the inclusion map is a homotopy equivalence. A spine is called simple if the complement of the $2$-sphere has abelian fundamental group. We prove that…

Geometric Topology · Mathematics 2024-05-10 Patrick Orson , Mark Powell

Let $r$ be a positive integer. An $r$-set is a pair $X= (V(X),R(X))$ consisting of a set $V(X)$ with a subset $R(X)$ of the direct product $V(X)^r$. The object of this paper is to investigate the Hom complexes of $r$-sets, which were…

Algebraic Topology · Mathematics 2016-04-20 Takahiro Matsushita

Structural independence is the (conditional) independence that arises from the structure rather than the precise numerical values of a distribution. We develop this concept and relate it to $d$-separation and structural causal models.…

Probability · Mathematics 2025-06-24 Matthias Georg Mayer

In this article we lay out the details of Fukaya's $A_\infty$-structure of the Morse complexe of a manifold possibly with boundary. We show that this $A_\infty$-structure is homotopically independent of the made choices. We emphasize the…

Algebraic Topology · Mathematics 2021-08-19 Hossein Abbaspour , Francois Laudenbach

A self-contained exposition is given of the topological and Galois-theoretic properties of the category of combinatorial 1-complexes, or graphs, very much in the spirit of Stallings. A number of classical, as well as some new results about…

Group Theory · Mathematics 2007-05-23 Brent Everitt

The independence polynomial $i(G,x)$ of a graph $G$ is the generating function of the numbers of independent sets of each size. A graph of order $n$ is very well-covered if every maximal independent set has size $n/2$. Levit and Mandrescu…

Combinatorics · Mathematics 2017-09-26 Jason I. Brown , Ben Cameron

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