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In this paper, we characterize all connected graphs with exactly three distinct normalized Laplacian eigenvalues of which one is equal to $1$, determine all connected bipartite graphs with at least one vertex of degree $1$ having exactly…

Combinatorics · Mathematics 2017-03-28 Xueyi Huang , Qiongxiang Huang

Within a framework of noncommutative geometry, we develop an analogue of (pseudo) Riemannian geometry on finite and discrete sets. On a finite set, there is a counterpart of the continuum metric tensor with a simple geometric…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Dimakis , F. Muller-Hoissen

New systems of Laplace (Casimir) operators for the orthogonal and symplectic Lie algebras are constructed. The operators are expressed in terms of paths in graphs related to matrices formed by the generators of these Lie algebras with the…

High Energy Physics - Theory · Physics 2009-10-28 Alexander Molev

We present monotonicity inequalities for certain functions involving eigenvalues of $p$-Laplacians on signed graphs with respect to $p$. Inspired by such monotonicity, we propose new spectrum-based graph invariants, called (variational)…

Spectral Theory · Mathematics 2023-11-01 Chuanyuan Ge , Shiping Liu , Dong Zhang

Spectral methods that are based on eigenvectors and eigenvalues of discrete graph Laplacians, such as Diffusion Maps and Laplacian Eigenmaps are often used for manifold learning and non-linear dimensionality reduction. It was previously…

Numerical Analysis · Mathematics 2015-06-02 Amit Singer , Hau-tieng Wu

A finite graph $\Gamma$ is called $G$-symmetric if $G$ is a group of automorphisms of $\Gamma$ which is transitive on the set of ordered pairs of adjacent vertices of $\Gamma$. We study a family of symmetric graphs, called the unitary…

Combinatorics · Mathematics 2015-03-25 Massimo Giulietti , Stefano Marcugini , Fernanda Pambianco , Sanming Zhou

This work explores the definiteness of the weighted graph Laplacian matrix with negative edge weights. The definiteness of the weighted Laplacian is studied in terms of certain matrices that are related via congruent and similarity…

Optimization and Control · Mathematics 2015-03-03 Daniel Zelazo , Mathias Bürger

The Laplacian matrix and its pseudo-inverse for a strongly connected directed graph is fundamental in computing many properties of a directed graph. Examples include random-walk centrality and betweenness measures, average hitting and…

Numerical Analysis · Mathematics 2020-09-16 Daniel Boley

On an infinite, radial metric tree graph we consider the corresponding Laplacian equipped with self-adjoint vertex conditions from a large class including $\delta$- and weighted $\delta'$-couplings. Assuming the numbers of different edge…

Spectral Theory · Mathematics 2017-07-04 Jonathan Rohleder , Christian Seifert

In this paper we consider the discrete Laplacian acting on 1-forms and we study its spectrum relative to the spectrum of the 0-form Laplacian. We show that the non zero spectrum can coincide for these Laplacians with the same nature. We…

Spectral Theory · Mathematics 2024-06-07 Colette Anné , Hela Ayadi , Marwa Balti , Nabila Torki-Hamza

We construct Riemannian manifolds with singular continuous spectrum embedded in the absolutely continuous spectrum of the Laplacian. Our manifolds are asymptotically hyperbolic with sharp curvature bounds.

Spectral Theory · Mathematics 2021-11-03 Svetlana Jitomirskaya , Wencai Liu

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

In this paper, we investigate the spectrum of a class of weighted Laplacians on Cayley graphs and determine under what conditions the corresponding eigenspaces are generically irreducible. Specifically, we analyze the spectrum on…

Spectral Theory · Mathematics 2024-06-05 Cristian F. Coletti , Lucas R. de Lima , Diego S. de Oliveira , Marcus A. M. Marrocos

We initiate the study of Hamiltonian cycles up to symmetries of the underlying graph. Our focus lies on the extremal case of Hamiltonian-transitive graphs, i.e., Hamiltonian graphs where, for every pair of Hamiltonian cycles, there is a…

Combinatorics · Mathematics 2026-05-06 Julia Baligacs , Sofia Brenner , Annette Lutz , Lena Volk

Let $N(X)$ be the Laplacian matrix of a directed graph obtained from the edge adjacency matrix of a graph $X.$ In this work, we study the bipartiteness property of the graph with the help of $N(X).$ We computed the spectrum of the edge…

Combinatorics · Mathematics 2023-09-28 Shivani Chauhan , A. Satyanarayana Reddy

We study the noncommutative differential geometry of the algebra of endomorphisms of any SU(n)-vector bundle. We show that ordinary connections on such SU(n)-vector bundle can be interpreted in a natural way as a noncommutative 1-form on…

dg-ga · Mathematics 2008-02-03 Michel Dubois-Violette , Thierry Masson

We study the convergence of the graph Laplacian of a random geometric graph generated by an i.i.d. sample from a $m$-dimensional submanifold $M$ in $R^d$ as the sample size $n$ increases and the neighborhood size $h$ tends to zero. We show…

Machine Learning · Statistics 2018-01-31 Nicolas Garcia Trillos , Moritz Gerlach , Matthias Hein , Dejan Slepcev

In this article, we relate the spectrum of the discrete magnetic Laplacian (DML) on a finite simple graph with two structural properties of the graph: the existence of a perfect matching and the existence of a Hamiltonian cycle of the…

Combinatorics · Mathematics 2022-07-11 J. S. Fabila-Carrasco , Fernando Lledó , Olaf Post

We present a geometrical construction of families of finite isospectral graphs labelled by different partitions of a natural number $r$ of given length $s$ (the number of summands). Isospectrality here refers to the discrete magnetic…

Spectral Theory · Mathematics 2024-01-30 John Stewart Fabila-Carrasco , Fernando Lledó , Olaf Post

Differential calculus on discrete spaces is studied in the manner of non-commutative geometry by representing the differential calculus by an operator algebra on a suitable Krein space. The discrete analogue of a (pseudo-)Riemannian metric…

Mathematical Physics · Physics 2007-05-23 Eric Forgy , Urs Schreiber