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Using the definition of colouring of $2$-edge-coloured graphs derived from $2$-edge-coloured graph homomorphism, we extend the definition of chromatic polynomial to $2$-edge-coloured graphs. We find closed forms for the first three…

Combinatorics · Mathematics 2020-07-28 I. Beaton , D. Cox , C. Duffy , N. Zolkavich

The largest matching root of a $k$-graph is the largest real root of its matching polynomial, which is equal to the maximum modulus of all the zeros of the matching polynomial. In this paper, we investigate the perturbation of the largest…

Combinatorics · Mathematics 2026-05-15 Jiang-Chao Wan , Yi Wang

Consider any random graph model where potential edges appear independently, with possibly different probabilities, and assume that the minimum expected degree is omega(ln n). We prove that the adjacency matrix and the Laplacian of that…

Combinatorics · Mathematics 2010-02-10 Roberto Imbuzeiro Oliveira

The symmetric edge polytope of a simple graph is a lattice polytope defined as the convex hull of a subset of the type A roots corresponding to the edges of the graph. In this article we prove a sharp lower bound for the number of edges of…

Combinatorics · Mathematics 2025-12-19 Giulia Codenotti , Roberto Riccardi , Lorenzo Venturello

We generalize two main theorems of matching polynomials of undirected simple graphs, namely, real-rootedness and the Heilmann-Lieb root bound. Viewing the matching polynomial of a graph $G$ as the independence polynomial of the line graph…

Combinatorics · Mathematics 2019-02-20 Jonathan Leake , Nick Ryder

Graph Laplacians on finite compact metric graphs are considered under the assumption that the matching conditions at the graph vertices are of either $\delta$ or $\delta'$ type. In either case, an infinite series of trace formulae which…

Mathematical Physics · Physics 2014-04-01 Yulia Ershova , Alexander V. Kiselev

Here we have investigated a few properties of the eigenvalues of normalized (geometric) graph Laplacian in different graphs. Preservation of eigenvalue 1 from a particular subgraph to the entire graph, the spectrum of the graph constructed…

Combinatorics · Mathematics 2014-03-07 Anirban Banerjee

We investigate how the metric dimension of infinite graphs change when we add edges to the graph. Our two main results: (1) there exists a growing sequence of graphs (under the subgraph relation, but without adding vertices) for which the…

Combinatorics · Mathematics 2023-03-15 Csaba Biró , Beth Novick , Daniela Olejnikova

We obtain new bounds for the Laplacian spectral radius of a signed graph. Most of these new bounds have a dependence on edge sign, unlike previously known bounds, which only depend on the underlying structure of the graph. We then use some…

Combinatorics · Mathematics 2011-03-25 Nathan Reff

The chromatic polynomial $\pi_{G}(k)$ of a graph $G$ can be viewed as counting the number of vertices in a family of coloring graphs $\mathcal C_k(G)$ associated with (proper) $k$-colorings of $G$ as a function of the number of colors $k$.…

Combinatorics · Mathematics 2025-05-06 Shamil Asgarli , Sara Krehbiel , Howard W. Levinson , Heather M. Russell

We conjecture a new lower bound on the algebraic connectivity of a graph that involves the number of vertices of high eccentricity in a graph. We prove that this lower bound implies a strengthening of the Laplacian Spread Conjecture. We…

Combinatorics · Mathematics 2022-01-13 Wayne Barrett , Emily Evans , H. Tracy Hall , Mark Kempton

A matching set $M$ in a graph $G$ is a collection of edges of $G$ such that no two edges from $M$ share a vertex. In this paper we consider some parameters related to the matching of regular graphs. We find the sixth coefficient of the…

Combinatorics · Mathematics 2017-10-23 Neda Soltani , Saeid Alikhani

The paper considers the behaviour of the number of paths of length $N$ on graphs with two heavy roots. Such vertices can be entropic traps. Numerical analysis is carried out for graphs with different degrees of root vertices. In the…

Statistical Mechanics · Physics 2023-02-14 Z. D. Matyushina

We consider a magnetic Laplacian with periodic magnetic potentials on periodic discrete graphs. Its spectrum consists of a finite number of bands, where degenerate bands are eigenvalues of infinite multiplicity. We obtain a specific…

Spectral Theory · Mathematics 2018-08-24 Evgeny Korotyaev , Natalia Saburova

A \emph{chromatic root} is a root of the chromatic polynomial of a graph. Any chromatic root is an algebraic integer. Much is known about the location of chromatic roots in the real and complex numbers, but rather less about their…

Combinatorics · Mathematics 2019-05-31 Peter J. Cameron , Kerri Morgan

We develop the theory of fractional revival in the quantum walk on a graph using its Laplacian matrix as the Hamiltonian. We first give a spectral characterization of Laplacian fractional revival, which leads to a polynomial time algorithm…

Combinatorics · Mathematics 2020-10-21 Ada Chan , Bobae Johnson , Mengzhen Liu , Malena Schmidt , Zhanghan Yin , Hanmeng Zhan

An invariant for cospectral graphs is a property shared by all cospectral graphs. In this paper, we establish three novel arithmetic invariants for cospectral graphs, revealing deep connections between spectral properties and combinatorial…

Combinatorics · Mathematics 2025-04-15 Yizhe Ji , Quanyu Tang , Wei Wang , Hao Zhang

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

We study some spectral properties of a matrix that is constructed as a combination of a Laplacian and an adjacency matrix of simple graphs. The matrix considered depends on a positive parameter, as such we consider the implications in…

Dynamical Systems · Mathematics 2024-08-02 Riccardo Bonetto , Hildeberto Jardón Kojakhmetov

We establish, for the first time, a Bochner-type integral representation for the logarithmic Laplacian on weighted graphs. Assuming stochastic completeness of the underlying graph, we further derive an explicit pointwise formula for this…

Analysis of PDEs · Mathematics 2025-07-29 Rui Chen , Wendi Xu