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We investigate the bottom of the spectra of infinite quantum graphs, i.e., Laplace operators on metric graphs having infinitely many edges and vertices. We introduce a new definition of the isoperimetric constant for quantum graphs and then…

Spectral Theory · Mathematics 2018-12-17 Aleksey Kostenko , Noema Nicolussi

A vertex colouring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Tucker conjectured that if every automorphism of a connected, locally finite graph moves infinitely many vertices, then there is…

Combinatorics · Mathematics 2020-07-21 Florian Lehner , Monika Pilśniak , Marcin Stawiski

The local chromatic number of a graph G is the number of colors appearing in the most colorful closed neighborhood of a vertex minimized over all proper colorings of G. We show that two specific topological obstructions that have the same…

Combinatorics · Mathematics 2007-05-23 Gábor Simonyi , Gábor Tardos , Siniša T. Vrećica

We prove that, for any connected graph on $N\geq 3$ vertices, the spectral gap from the value $1$ with respect to the normalized Laplacian is at most $1/2$. Moreover, we show that equality is achieved if and only if the graph is either a…

Combinatorics · Mathematics 2023-07-07 Jürgen Jost , Raffaella Mulas , Dong Zhang

We study topological Poincar\'e type inequalities on general graphs. We characterize graphs satisfying such inequalities and then turn to the best constants in these inequalities. Invoking suitable metrics we can interpret these constants…

Functional Analysis · Mathematics 2018-01-30 Daniel Lenz , Marcel Schmidt , Peter Stollmann

Hypergraphs require higher-dimensional representations, which makes it more difficult to compute and interpret their spectral properties. This survey article uses the framework of hypermatrices to give an in-depth overview of the spectral…

History and Overview · Mathematics 2025-07-21 Shashwath S Shetty , K Arathi Bhat

In this thesis, we analyze the stochastic completeness of a heat kernel on graphs which is a function of three variables: a pair of vertices and a continuous time, for infinite, locally finite, connected graphs. For general graphs, a…

Spectral Theory · Mathematics 2007-12-11 Radoslaw K. Wojciechowski

We show that every $d$-regular bipartite Borel graph admits a Baire measurable $k$-regular spanning subgraph if and only if $d$ is odd or $k$ is even. This gives the first example of a locally checkable coloring problem which is known to…

Logic · Mathematics 2024-08-20 Matt Bowen , Clinton T. Conley , Felix Weilacher

For the set of graphs with a given degree sequence, consisting of any number of $2's$ and $1's$, and its subset of bipartite graphs, we characterize the optimal graphs who maximize and minimize the number of $m$-matchings. We find the…

Combinatorics · Mathematics 2008-01-16 S. Friedland , E. Krop , K. Markström

We give a short proof of a bound on the list chromatic number of graphs $G$ of maximum degree $\Delta$ where each neighbourhood has density at most $d$, namely $\chi_\ell(G) \le (1+o(1)) \frac{\Delta}{\ln \frac{\Delta}{d+1}}$ as…

Combinatorics · Mathematics 2021-11-29 François Pirot , Eoin Hurley

We study a metric on the set of finite graphs in which two graphs are considered to be similar if they have similar bounded dimensional "factors". We show that limits of convergent graph sequences in this metric can be represented by…

Combinatorics · Mathematics 2016-12-07 Dávid Kunszenti-Kovács , László Lovász , Balázs Szegedy

We introduce a new graph invariant that measures fractional covering of a graph by cuts. Besides being interesting in its own right, it is useful for study of homomorphisms and tension-continuous mappings. We study the relations with…

Combinatorics · Mathematics 2015-11-24 Robert Šámal

A graph $G$ is said to be \emph{determined by its spectrum} if any graph having the same spectrum as $G$ is isomorphic to $G$. Let $K_n \setminus P_{\ell}$ be the graph obtained from $K_n$ by removing edges of $P_\ell$, where $P_\ell$ is a…

Combinatorics · Mathematics 2018-04-24 Lihuan Mao , Sebastian M. Cioabă , Wei Wang

We study the spectral convergence of a symmetrized Graph Laplacian matrix induced by a Gaussian kernel evaluated on pairs of embedded data, sampled from a manifold with boundary, a sub-manifold of $\mathbb{R}^m$. Specifically, we deduce the…

Numerical Analysis · Mathematics 2025-05-20 J. Wilson Peoples , John Harlim

The authors study the spectral theory of self-adjoint operators that are subject to certain types of perturbations. An iterative introduction of infinitely many randomly coupled rank-one perturbations is one of our settings. Spectral…

Spectral Theory · Mathematics 2019-02-08 Dale Frymark , Constanze Liaw

We apply Cauchy's interlacing theorem to derive some eigenvalue bounds to the chromatic number using the normalized Laplacian matrix, including a combinatorial characterization of when equality occurs. Further, we introduce some new…

Combinatorics · Mathematics 2019-10-16 Gabriel Coutinho , Rafael Grandsire , Célio Passos

A coloring of vertices of a graph is called perfect if, for every vertex, the collection of colors of its neighbors depends only on its own color. The correspondent color partition of vertices is called equitable. We note that a number of…

Combinatorics · Mathematics 2025-05-16 Vladimir N. Potapov

We prove spectral localization for infinite metric graphs with a self-adjoint Laplace operator and a random potential. To do so we adapt the multiscale analysis (MSA) from the R^d-case to metric graphs. In the MSA a covering of the graph is…

Spectral Theory · Mathematics 2012-08-31 Carsten Schubert

Regular and distance-regular characterizations of general graphs are well-known. In particular, the spectral excess theorem states that a connected graph G is distance-regular if and only if its spectral excess (a number that can be…

Combinatorics · Mathematics 2013-09-27 A. Abiad , C. Dalfò , M. A. Fiol

A matching in a graph is uniquely restricted if no other matching covers exactly the same set of vertices. This notion was defined by Golumbic, Hirst, and Lewenstein and studied in a number of articles. Our contribution is twofold. We…

Combinatorics · Mathematics 2016-11-22 Julien Baste , Dieter Rautenbach , Ignasi Sau
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