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Related papers: Hearing Euler characteristic of graphs

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Let $L$ be a set of positive integers. We call a (directed) graph $G$ an $L$\emph{-cycle graph} if all cycle lengths in $G$ belong to $L$. Let $c(L,n)$ be the maximum number of cycles possible in an $n$-vertex $L$-cycle graph (we use…

Combinatorics · Mathematics 2016-10-12 Dániel Gerbner , Balázs Keszegh , Cory Palmer , Balázs Patkós

As a discrete analogue of Kac's celebrated question on "hearing the shape of a drum", and towards a practical graph isomorphism test, it is of interest to understand which graphs are determined up to isomorphism by their spectrum (of their…

Combinatorics · Mathematics 2024-11-19 Illya Koval , Matthew Kwan

In this paper we investigate some properties of the Fiedler vector, the so-called first non-trivial eigenvector of the Laplacian matrix of a graph. There are important results about the Fiedler vector to identify spectral cuts in graphs but…

Discrete Mathematics · Computer Science 2023-06-08 Julien Lefevre , Justine Fraize , David Germanaud

We introduce new algebro-topological invariants of directed networks, based on the topological construction of the directed clique complex. The shape of the underlying directed graph is encoded in a way that can be studied mathematically to…

Neurons and Cognition · Quantitative Biology 2016-04-06 Paolo Masulli , Alessandro E. P. Villa

This is a note on three graph parameters motivated by the Euler-Poincare characteristic for simplicial complex. We show those three graph parameters of a given connected graph $G$ is greater than or equal to that of the complete graph with…

Combinatorics · Mathematics 2012-11-28 Hanbaek Lyu

Computer or communication networks are so designed that they do not easily get disrupted under external attack and, moreover, these are easily reconstructible if they do get disrupted. These desirable properties of networks can be measured…

Combinatorics · Mathematics 2011-09-23 T. C. E. Cheng , Yinkui Li , Chuandong Xu , Shenggui Zhang

A graph $G$ is called collapsible if for every even subset $R\subseteq V(G)$, there is a spanning connected subgraph $H$ of $G$ such that $R$ is the set of vertices of odd degree in $H$. A graph is the reduction of $G$ if it is obtained…

Combinatorics · Mathematics 2016-01-08 Wei-Guo Chen , Zhi-Hong Chen , Mei Lu

Threshold graphs are graphs that can be characterized in a number of different ways. For example, they are graphs that are $P_4,\ C_4,\ 2K_2$--free. They may also be characterized by a finite sequence of positive integers $a_1, \ldots,…

Combinatorics · Mathematics 2026-05-07 James L. Borg , Irene Sciriha , Zoia Sherman

Given a graph and one of its weighted Laplacian matrix, a Fiedler vector is an eigenvector with respect to the second smallest eigenvalue. The Fiedler vectors have been used widely for graph partitioning, graph drawing, spectral clustering,…

Combinatorics · Mathematics 2024-10-15 Jephian C. -H. Lin , Mahsa N Shirazi

We consider 15 properties of labeled random graphs that are of interest in the graph-theoretical and the graph mining literature, such as clustering coefficients, centrality measures, spectral radius, degree assortativity, treedepth,…

Social and Information Networks · Computer Science 2022-06-24 Hang Chen , Vahan Huroyan , Stephen Kobourov , Myroslav Kryven

An \emph{adjacency labeling scheme} for a given class of graphs is an algorithm that for every graph $G$ from the class, assigns bit strings (labels) to vertices of $G$ so that for any two vertices $u,v$, whether $u$ and $v$ are adjacent…

Data Structures and Algorithms · Computer Science 2020-04-20 Marthe Bonamy , Cyril Gavoille , Michal Pilipczuk

An eigenvalue of the adjacency matrix of a graph is said to be \emph{main} if the all-1 vector is not orthogonal to the associated eigenspace. In this work, we approach the main eigenvalues of some graphs. The graphs with exactly two main…

Combinatorics · Mathematics 2026-02-17 Nair Abreu , Domingos M. Cardoso , Francisca A. M. França , Cybele T. M. Vinagre

Many natural and social systems develop complex networks, that are usually modelled as random graphs. The eigenvalue spectrum of these graphs provides information about their structural properties. While the semi-circle law is known to…

Statistical Mechanics · Physics 2009-11-07 Illes J. Farkas , Imre Derenyi , Albert-Laszlo Barabasi , Tamas Vicsek

The Euler Characteristic Transform (ECT) has proven to be a powerful representation, combining geometrical and topological characteristics of shapes and graphs. However, the ECT was hitherto unable to learn task-specific representations. We…

Machine Learning · Computer Science 2024-03-20 Ernst Roell , Bastian Rieck

In this article, we study Euler characteristic techniques in topological data analysis. Pointwise computing the Euler characteristic of a family of simplicial complexes built from data gives rise to the so-called Euler characteristic…

Machine Learning · Computer Science 2024-07-25 Olympio Hacquard , Vadim Lebovici

The Wiener index of a connected graph is defined as the sum of the distances between all unordered pair of its vertices. In this paper, we characterize the graphs which extremize the Wiener index among all graphs on $n$ vertices with $k$…

Combinatorics · Mathematics 2019-08-01 Dinesh Pandey , Kamal Lochan Patra

The Evasiveness conjecture have been proved for properties of graphs on a prime-power number of vertices and the six vertices case. The ten vertices case is still unsolved. In this paper we study the size of the automorphism group of a…

Algebraic Topology · Mathematics 2016-03-15 Andres Angel , Jerson Borja

Let $G = (V, E)$ be a graph. We define matrices $M(G; \alpha, \beta)$as $\alpha D + \beta A$, where $\alpha$, $\beta$ are real numbers such that $(\alpha, \beta) \neq (0, 0)$ and $D$ and $A$ are the diagonal matrix and adjacency matrix of…

Combinatorics · Mathematics 2024-10-24 Rao Li

Not every graph has an Eulerian tour. But every finite, strongly connected graph has a multi-Eulerian tour, which we define as a closed path that uses each directed edge at least once, and uses edges e and f the same number of times…

Combinatorics · Mathematics 2015-09-22 Matthew Farrell , Lionel Levine

Let $n\ge 1$ be an integer and $\mathbb{F}_q$ be a finite field of characteristic $p$ with $q$ elements. In this paper, it is proved that the Wenger graph $W_n(q)$ and linearized Wenger graph $L_m(q)$ are edge-girth-regular…

Combinatorics · Mathematics 2023-11-09 Fuyuan Yang , Qiang Sun , Chao Zhang