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We prove new properties of the non-backtracking graph and the non-backtracking Laplacian for graphs. In particular, among other results, we prove that two simple graphs are isomorphic if and only if their corresponding non-backtracking…

Combinatorics · Mathematics 2023-05-30 Raffaella Mulas , Dong Zhang , Giulio Zucal

According to a recent conjecture, isospectral objects have different nodal count sequences. We study generalized Laplacians on discrete graphs, and use them to construct the first non-trivial counter-examples to this conjecture. In…

Mathematical Physics · Physics 2016-11-25 Idan Oren , Ram Band

We consider a non self-adjoint Laplacian on a directed graph with non symmetric edge weights. We analyse spectral properties of this Laplacian under a Kirchhoff assumption. Moreover we establish isoperimet-ric inequalities in terms of the…

Spectral Theory · Mathematics 2018-01-15 Marwa Balti

This is an expository article on the question of whether zero lies in the spectrum of the Laplace-Beltrami operator acting on differential forms on a manifold.

dg-ga · Mathematics 2008-02-03 John Lott

Laplacian operators on finite compact metric graphs are considered under the assumption that matching conditions at graph vertices are of $\delta$ and $\delta'$ types. An infinite series of trace formulae is obtained which link together two…

Spectral Theory · Mathematics 2014-11-06 Yulia Ershova , Irina I. Karpenko , Alexander V. Kiselev

In this paper we define signless Laplacian matrix of a hypergraph and obtain structural properties from its eigenvalues. We generalize several known results for graphs, relating the spectrum of this matrix with structural parameters of the…

Spectral Theory · Mathematics 2024-08-12 Kauê Cardoso , Vilmar Trevisan

The spectral theory of the normalized Laplacian for chemical hypergraphs is further investigated. The signless normalized Laplacian is introduced and it is shown that its spectrum for classical hypergraphs coincides with the spectrum of the…

Combinatorics · Mathematics 2022-11-09 Eleonora Andreotti , Raffaella Mulas

Laplace operators on finite compact metric graphs are considered under the assumption that matching conditions at graph vertices are of $\delta$ and $\delta'$ types. Assuming rational independence of edge lengths, necessary and sufficient…

Spectral Theory · Mathematics 2015-12-09 Yulia Ershova , Irina I. Karpenko , Alexander V. Kiselev

In this paper, we compute the Laplacian spectrum of non-commuting graphs of some classes of finite non-abelian groups. Our computations reveal that the non-commuting graphs of all the groups considered in this paper are L-integral. We also…

Group Theory · Mathematics 2017-05-04 Parama Dutta , Jutirekha Dutta , Rajat Kanti Nath

Motivated by discrete Laplacian differential operators with various accuracy orders in numerical analysis, we introduce new matrices attached to a simple graph that can be considered graph Laplacians with higher accuracy. In particular, we…

Combinatorics · Mathematics 2025-04-09 Mary Yoon

Let $F_{a_1,\dots,a_k}$ be a graph consisting of $k$ cycles of odd length $2a_1+1,\dots, 2a_k+1$, respectively which intersect in exactly a common vertex, where $k\geq1$ and $a_1\ge a_2\ge \cdots\ge a_k\ge 1$. In this paper, we present a…

Combinatorics · Mathematics 2021-08-10 Ming-Zhu Chen , A-Ming Liu , Xiao-Dong Zhang

We consider a non self-adjoint Laplacian on a directed graph with non symmetric edge weights. We give necessary conditions for this Laplacian to be sectorial. We introduce a special self-adjoint operator and compare its essential spectrum…

Spectral Theory · Mathematics 2018-01-08 Colette Anné , Marwa Balti , Nabila Torki-Hamza

In this paper we investigate a spectra of the Laplacian matrix of cyclic groups using the properties of their characteristic polynomials. We have proved several assertions about the relationship between the spectra of different groups.

Representation Theory · Mathematics 2011-05-19 Dmitriy Goltsov

We study the relationship between the adjacency matrix and the discrete Laplacian acting on 1-forms. We also prove that if the adjacency matrix is bounded from below it is not necessarily essentially self-adjoint. We discuss the question of…

Spectral Theory · Mathematics 2015-05-25 Hatem Baloudi , Sylvain Golenia , Aref Jeribi

We study zero modes of Laplacians on compact and non-compact metric graphs with general self-adjoint vertex conditions. In the first part of the paper the number of zero modes is expressed in terms of the trace of a unitary matrix…

Mathematical Physics · Physics 2015-05-27 Jens Bolte , Sebastian Egger , Frank Steiner

For a given infinite connected graph $G=(V,E)$ and an arbitrary but fixed conductance function $c$, we study an associated graph Laplacian $\Delta_{c}$; it is a generalized difference operator where the differences are measured across the…

Functional Analysis · Mathematics 2015-06-19 Palle Jorgensen , Feng Tian

There is a deep and interesting connection between the topological properties of a graph and the behaviour of the dynamical system defined on it. We analyse various kind of graphs, with different contrasting connectivity or degree…

Combinatorics · Mathematics 2017-05-01 Barbara Giunti , Vincenzo Perri

This paper explores interlacing inequalities in the Laplacian spectrum of signed cycles and investigates interlacing relationship between the spectrum of the net-Laplacian of a signed graph and its subgraph formed by removing a vertex…

Combinatorics · Mathematics 2023-10-19 Satyam Guragain , Ravi Srivastava

We consider Laplace operators on periodic discrete graphs perturbed by guides, i.e., graphs which are periodic in some directions and finite in other ones. The spectrum of the Laplacian on the unperturbed graph is a union of a finite number…

Spectral Theory · Mathematics 2017-02-07 Evgeny Korotyaev , Natalia Saburova

We consider a Laplacian on periodic discrete graphs. Its spectrum consists of a finite number of bands. In a class of periodic 1-forms, i.e., functions defined on edges of the periodic graph, we introduce a subclass of minimal forms with a…

Spectral Theory · Mathematics 2019-05-28 E. Korotyaev , N. Saburova