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The matching complex $M(G)$ of a simple graph $G$ is the simplicial complex consisting of the matchings on $G$. The matching complex $M(G)$ is isomorphic to the independence complex of the line graph $L(G)$. Braun and Hough introduced a…

Combinatorics · Mathematics 2019-07-01 Takahiro Matsushita

The $m$-neighbor complex of a graph is the simplicial complex in which faces are sets of vertices with at least $m$ common neighbors. We consider these complexes for Erdos-Renyi random graphs and find that for certain explicit families of…

Combinatorics · Mathematics 2023-09-12 Eric Babson , Jan Spaliński

Inspired by work of Fr\"oberg (1990), and Eagon and Reiner (1998), we define the \emph{total $k$-cut complex} of a graph $G$ to be the simplicial complex whose facets are the complements of independent sets of size $k$ in $G$. We study the…

Graphs with given k vertices generate an (acyclic) simplicial complex. We describe the homology of its quotient complex, formed by all connected graphs, and demonstrate its applications to the topology of braid groups, knot theory,…

Combinatorics · Mathematics 2014-09-23 V. A. Vassiliev

The matching complex $M(G)$ of a graph $G$ is the set of all matchings in $G$. A Buchsbaum simplicial complex is a generalization of both a homology manifold and a Cohen--Macaulay complex. We give a complete characterization of the graphs…

Combinatorics · Mathematics 2023-01-20 Bennet Goeckner , Fran Herr , Legrand Jones , Rowan Rowlands

The dominance complex $D(G)$ of a simple graph $G = (V,E)$ is the simplicial complex consisting of the subsets of $V$ whose complements are dominating. We show that the connectivity of $D(G)$ plus $2$ is a lower bound for the vertex cover…

Combinatorics · Mathematics 2022-12-06 Takahiro Matsushita

Let $G$ be a finite simple graph. The line graph $L(G)$ represents the adjacencies between edges of $G$. We define first the line simplicial complex $\Delta_L(G)$ of $G$ containing Gallai and anti-Gallai simplicial complexes…

Algebraic Topology · Mathematics 2017-08-04 Imran Ahmed , Shahid Muhmood

A \v{C}ech complex of a finite simple graph $G$ is a nerve complex of balls in the graph, with one ball centered at each vertex. More precisely, let the \v{C}ech complex $\mathcal{N}(G,r)$ be the nerve of all closed balls of radius…

Combinatorics · Mathematics 2023-11-21 Henry Adams , Samir Shukla , Anurag Singh

We introduce the notion of r-neighborhood complex for a positive integer r, which is a natural generalization of Lovasz neighborhood complex. The topologies of these complexes give some obstructions of the existence of graph maps. We…

Combinatorics · Mathematics 2013-05-14 Takahiro Matsushita

We show that the independence complexes of generalised Mycielskian of complete graphs are homotopy equivalent to a wedge sum of spheres, and determine the number of copies and the dimensions of these spheres. We also prove that the…

Combinatorics · Mathematics 2022-04-29 Shuchita Goyal , Samir Shukla , Anurag Singh

The matching complex of a graph is the simplicial complex whose vertex set is the set of edges of the graph with a face for each independent set of edges. In this paper we completely characterize the pairs (graph, matching complex) for…

Combinatorics · Mathematics 2020-03-24 Margaret Bayer , Bennet Goeckner , Marija Jelić Milutinović

For a given finite class of finite graphs H, a graph G is called a realization of H if the neighbourhood of its any vertex induces the subgraph isomorphic to a graph of H. We consider the following problem known as the Generalized…

Discrete Mathematics · Computer Science 2009-09-25 V. Naidenko , Yu. Orlovich

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

We introduce $k$-robust clique complexes, a family of simplicial complexes that generalizes the traditional clique complex. Here, a subset of vertices forms a simplex provided it does not contain an independent set of size $k$. We…

Combinatorics · Mathematics 2026-04-02 Marek Filakovský

A graph is Hamiltonian if it contains a cycle which goes through all vertices exactly once. Determining if a graph is Hamiltonian is known as a NP-complete problem and no satisfactory characterization for these graphs has been found. In…

Combinatorics · Mathematics 2013-08-29 Thierry Vallee

The matching complex of a simple graph $G$ is a simplicial complex consisting of the matchings on $G$. Jeli\'c Milutinovi\'c et al. studied the matching complexes of the polygonal line tilings, and they gave a lower bound for the…

Combinatorics · Mathematics 2022-06-17 Takahiro Matsushita

An open neighbourhood locating-dominating set is a set $S$ of vertices of a graph $G$ such that each vertex of $G$ has a neighbour in $S$, and for any two vertices $u,v$ of $G$, there is at least one vertex in $S$ that is a neighbour of…

Combinatorics · Mathematics 2022-01-25 Florent Foucaud , Narges Ghareghani , Aida Roshany-Tabrizi , Pouyeh Sharifani

A sequence of vertices $(v_1,\, \dots , \,v_k)$ of a graph $G$ is called a {\it dominating closed neighborhood sequence} if $\{v_1,\, \dots , \,v_k\}$ is a dominating set of $G$ and $N[v_i]\nsubseteq \cup _{j=1}^{i-1} N[v_j]$ for every $i$.…

Combinatorics · Mathematics 2020-11-09 Aysel Erey

The neighbor connectivity of a graph $G$ is the least number of vertices such that removing their closed neighborhoods from $G$ results in a graph that is disconnected, complete or empty. If a~graph is used to model the topology of an…

Discrete Mathematics · Computer Science 2019-10-29 Tomáš Dvořák , Mei-Mei Gu

Simplicial complexes can be viewed as high dimensional generalizations of graphs that explicitly encode multi-way ordered relations between vertices at different resolutions, all at once. This concept is central towards detection of higher…

Machine Learning · Computer Science 2022-07-05 Alexandros Dimitrios Keros , Vidit Nanda , Kartic Subr