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Graph independence (also known as $\epsilon$-independence or $\lambda$-independence) is a mixture of classical independence and free independence corresponding to graph products or groups and operator algebras. Using conjugation by certain…

This paper investigates the shellability of $r$-independence complexes $\mathcal{I}_r(G)$, a generalization of classical independence complexes introduced by Paolini and Salvetti. For a graph $G$, a subset $A \subseteq V(G)$ is…

Combinatorics · Mathematics 2025-09-24 Arka Ghosh , S Selvaraja

Graph parameters such as the clique number, the chromatic number, and the independence number are central in many areas, ranging from computer networks to linguistics to computational neuroscience to social networks. In particular, the…

Computational Complexity · Computer Science 2020-12-15 Fabian Frei , Edith Hemaspaandra , Jörg Rothe

This paper makes some preliminary observations towards an extension of current work on graphs defined on groups to simplicial complexes. I define a variety of simplicial complexes on a group which are preserved by automorphisms of the…

Combinatorics · Mathematics 2024-11-04 Peter J. Cameron

We determine the homotopy types of the independence complexes of the $(n \times 6)$-square grid graphs. In fact, we show that these complexes are homotopy equivalent to wedges of spheres.

Algebraic Topology · Mathematics 2023-01-31 Takahiro Matsushita , Shun Wakatsuki

We show that the discrete versions of the systolic inequality that estimate the number of vertices of a simplicial complex from below have substantial applications to graphs, the one-dimensional simplicial complexes. Almost directly they…

Combinatorics · Mathematics 2022-11-01 Alexander Kamal , Roman Karasev

In this paper we study unimodality problems for the independence polynomial of a graph, including unimodality, log-concavity and reality of zeros. We establish recurrence relations and give factorizations of independence polynomials for…

Combinatorics · Mathematics 2010-08-17 Yi Wang , Bao-Xuan Zhu

Star clusters are ideal tracers of star formation activity in systems outside the volume that can be studied using individual, resolved stars. These unresolved clusters span orders of magnitude in brightness and mass, and their formation is…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-20 I. S. Konstantopoulos , K. Fedotov , S. C. Gallagher , A. Maybhate , P. R. Durrell , J. C. Charlton

Testing for independence between graphs is a problem that arises naturally in social network analysis and neuroscience. In this paper, we address independence testing for inhomogeneous Erd\H{o}s-R\'{e}nyi random graphs on the same vertex…

Methodology · Statistics 2023-04-19 Yukun Song , Carey E. Priebe , Minh Tang

We construct a new graph on 120 vertices whose quantum and classical independence numbers are different. At the same time, we construct an infinite family of graphs whose quantum chromatic numbers are smaller than the classical chromatic…

Combinatorics · Mathematics 2024-02-09 Chris Godsil , Mariia Sobchuk

We study the independence complexes of families of well-covered circulant graphs discovered by Boros-Gurvich-Milani\v{c}, Brown-Hoshino, and Moussi. Because these graphs are well-covered, their independence complexes are pure simplicial…

Combinatorics · Mathematics 2015-05-13 Jonathan Earl , Kevin N. Vander Meulen , Adam Van Tuyl

For $r\geq 1$, the $r$-independence complex of a graph $G$, denoted Ind$_r(G)$, is a simplicial complex whose faces are subsets $A \subseteq V(G)$ such that each component of the induced subgraph $G[A]$ has at most $r$ vertices. In this…

Combinatorics · Mathematics 2020-01-22 Priyavrat Deshpande , Samir Shukla , Anurag Singh

A {\it star-factor} of a graph $G$ is a spanning subgraph of $G$ such that each of its component is a star. Clearly, every graph without isolated vertices has a star factor. A graph $G$ is called {\it star-uniform} if all star-factors of…

Combinatorics · Mathematics 2007-07-03 Mikio Kano , Yunjian Wu , Qinglin Yu

In this paper, we consider the problem of a star coloring. In general case the problems in NP-complete. We establish the star chromatic number for splitting graph of complete and complete bipartite graphs, as well of paths and cycles. Our…

Combinatorics · Mathematics 2017-05-29 Hanna Furmańczyk , Kowsalya V , Vernold Vivin J

Simplicial complexes are higher-order combinatorial structures which have been used to represent real-world complex systems. In this paper, we concentrate on the local patterns in simplicial complexes called simplets, a generalization of…

Social and Information Networks · Computer Science 2023-04-26 Hyunju Kim , Jihoon Ko , Fanchen Bu , Kijung Shin

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

The Hom complex $\mathrm{Hom}(G, H)$ of graphs is a simplicial complex associated to a pair of graphs $G$ and $H$, and its homotopy type is of interest in the graph coloring problem and the homomorphism reconfiguration problem. In this…

Combinatorics · Mathematics 2026-02-04 Takahiro Matsushita

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

By an independent set in a simple graph $G$, we mean a set of pairwise non-adjacent vertices in $G$. The independence polynomial of $G$ is defined as $I_G(z)=a_0 + a_1 z + a_2 z^2+\cdots+a_\alpha z^{\alpha}$, where $a_i$ is the number of…

Combinatorics · Mathematics 2025-05-28 Garima Khetawat , Moumita Manna , Tarakanta Nayak

We study the behaviour of clique complexes of graphs under the operation of taking graph powers. As an example we compute the clique complexes of powers of cycles, or, in other words, the independence complexes of circular complete graphs.

Combinatorics · Mathematics 2015-03-19 Michal Adamaszek