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Related papers: On independence complexes of graph products

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We investigate a notion of $\times$-homotopy of graph maps that is based on the internal hom associated to the categorical product in the category of graphs. It is shown that graph $\times$-homotopy is characterized by the topological…

Combinatorics · Mathematics 2008-07-07 Anton Dochtermann

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

We study the question of polytopality of graphs: when is a given graph the graph of a polytope? We first review the known necessary conditions for a graph to be polytopal, and we provide several families of graphs which satisfy all these…

Metric Geometry · Mathematics 2013-04-30 Julian Pfeifle , Vincent Pilaud , Francisco Santos

We show that the dominance complex $\mathcal{D}(G)$ of a graph $G$ coincides with the combinatorial Alexander dual of the neighborhood complex $\mathcal{N}(\overline{G})$ of the complement of $G$. Using this, we obtain a relation between…

Combinatorics · Mathematics 2024-11-01 Takahiro Matsushita , Shun Wakatsuki

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

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

We investigate when the independence complex of $G[H]$, the lexicographical product of two graphs $G$ and $H$, is either vertex decomposable or shellable. As an application, we construct an infinite family of graphs with the property that…

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

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 study the free product of rooted graphs and its various decompositions using quantum probabilistic methods. We show that the free product of rooted graphs is canonically associated with free independence, which completes the proof of the…

Combinatorics · Mathematics 2014-07-25 Luigi Accardi , Romuald Lenczewski , Rafal Salapata

We show that there are polynomial-time algorithms to compute maximum independent sets in the categorical products of two cographs and two splitgraphs. We show that the ultimate categorical independence ratio is computable in polynomial time…

Discrete Mathematics · Computer Science 2013-05-21 W. Hon , T. Kloks , S. Liu , S. Poon , Y. Wang

Topological methods have emerged as valuable tools for analyzing the structural properties of directed graphs, particularly connectome data in computational neuroscience. This paper investigates the construction of topological spaces from…

Algebraic Topology · Mathematics 2026-05-04 Pedro Conceição

In this work we study the homotopy type of multipath complexes of bidirectional path graphs and polygons, motivated by works of Vre\'cica and \v{Z}ivaljevi\'c on cycle-free chessboard complexes (that is, multipath complexes of complete…

Combinatorics · Mathematics 2026-01-12 Luigi Caputi , Carlo Collari , Jason P. Smith

A Hamiltonian path (a Hamiltonian cycle) in a graph is a path (a cycle, respectively) that traverses all of its vertices. The problems of deciding their existence in an input graph are well-known to be NP-complete, in fact, they belong to…

Discrete Mathematics · Computer Science 2025-04-02 Nikola Jedličková , Jan Kratochvíl

The matching complex $\mathsf{M}(G)$ of a graph $G$ is a simplicial complex whose simplices are matchings in $G$. These complexes appear in various places and found applications in many areas of mathematics including computational geometry,…

Combinatorics · Mathematics 2026-04-24 Raju Kumar Gupta , Sourav Sarkar , Sagar S. Sawant , Samir Shukla

To a digraph with a choice of certain integral basis, we construct a CW complex, whose integral singular cohomology is canonically isomorphic to the path cohomology of the digraph as introduced in \cite{GLMY}. The homotopy type of the CW…

Combinatorics · Mathematics 2014-09-23 An Huang , Shing-Tung Yau

In this paper, we investigate Hamiltonian path problem in the context of split graphs, and produce a dichotomy result on the complexity of the problem. Our main result is a deep investigation of the structure of $K_{1,4}$-free split graphs…

Discrete Mathematics · Computer Science 2017-11-28 P. Renjith , N. Sadagopan

The independence polynomial of a graph is the generating polynomial for the number of independent sets of each size, and its roots are called {\em independence roots}. We investigate the stability of such polynomials, that is, conditions…

Combinatorics · Mathematics 2018-02-08 Jason Brown , Ben Cameron

We generalize some homotopy calculation techniques such as splittings and matching trees that are introduced for the computations in the case of the independence complexes of graphs to arbitrary simplicial complexes, and exemplify their…

Combinatorics · Mathematics 2015-01-28 Demet Taylan

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

The independence complex $\mathrm{Ind}(G)$ of a graph $G$ is the simplicial complex formed by its independent sets. This article introduces a deformation of the simplicial boundary map of $\mathrm{Ind}(G)$ that gives rise to a double…

Algebraic Topology · Mathematics 2020-10-01 Marko Berghoff