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Related papers: On the inverse eigenvalue problem for block graphs

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All graphs considered are simple and undirected. The Inverse Eigenvalue Problem of a Graph $G$ (IEP-G) aims to find all possible spectra for matrices whose $(i,j)-$entry, for $i\neq j$, is nonzero precisely when $i$ is adjacent to $j$. A…

Combinatorics · Mathematics 2023-03-20 Roberto C. Díaz , Ana I. Julio

A hollow matrix described by a graph $G$ is a real symmetric matrix having all diagonal entries equal to zero and with the off-diagonal entries governed by the adjacencies in $G$. For a given graph $G$, the determination of all possible…

Combinatorics · Mathematics 2023-06-23 F. Scott Dahlgren , Zachary Gershkoff , Leslie Hogben , Sara Motlaghian , Derek Young

Let $G$ be an undirected graph on $n$ vertices and let $S(G)$ be the set of all $n \times n$ real symmetric matrices whose nonzero off-diagonal entries occur in exactly the positions corresponding to the edges of $G$. The inverse eigenvalue…

Spectral Theory · Mathematics 2014-01-10 Polona Oblak , Helena Šmigoc

The inverse eigenvalue problem studies the possible spectra among matrices whose off-diagonal entries have their zero-nonzero patterns described by the adjacency of a graph $G$. In this paper, we refer to the $i$-nullity pair of a matrix…

Combinatorics · Mathematics 2023-10-24 Aida Abiad , Bryan A. Curtis , Mary Flagg , H. Tracy Hall , Jephian C. -H. Lin , Bryan Shader

The inverse eigenvalue problem of a graph $G$ is the problem of characterizing all lists of eigenvalues of real symmetric matrices whose off-diagonal pattern is prescribed by the adjacencies of $G$. The strong spectral property is a…

Combinatorics · Mathematics 2023-06-07 Jephian C. -H. Lin , Polona Oblak , Helena Šmigoc

The inverse eigenvalue problem of a given graph $G$ is to determine all possible spectra of real symmetric matrices whose off-diagonal entries are governed by the adjacencies in $G$. Barrett et al. introduced the Strong Spectral Property…

For a given graph $G$, we aim to determine the possible realizable spectra for a generalized (or sometimes referred to as a weighted) Laplacian matrix associated with $G$. This new specialized inverse eigenvalue problem is considered for…

Combinatorics · Mathematics 2024-12-03 Shaun Fallat , Himanshu Gupta , Jephian C. -H. Lin

In this paper, we initiate the study of the inverse eigenvalue problem for probe graphs. A probe graph is a graph whose vertices are partitioned into probe vertices and non-probe vertices such that the non-probe vertices form an independent…

Combinatorics · Mathematics 2024-03-01 Emelie Curl , Jürgen Kritschgau , Carolyn Reinhart , Hein van der Holst

A discrete Schr\"odinger operator of a graph $G$ is a real symmetric matrix whose $i,j$-entry, $i \neq j$, is negative if $\{i,j\}$ is an edge and zero if it is not an edge, while diagonal entries can be any real numbers. The discrete…

Combinatorics · Mathematics 2025-10-28 Anzila Laikhuram , Jephian C. -H. Lin

For a graph $G$, we associate a family of real symmetric matrices, $\mathcal{S}(G)$, where for any $M \in \mathcal{S}(G)$, the location of the nonzero off-diagonal entries of $M$ are governed by the adjacency structure of $G$. The ordered…

The inverse eigenvalue problem of a graph studies the real symmetric matrices whose off-diagonal pattern is prescribed by the adjacencies of the graph. The strong spectral property (SSP) is an important tool for this problem. This note…

Combinatorics · Mathematics 2022-04-19 Shaun M. Fallat , H. Tracy Hall , Jephian C. -H. Lin , Bryan L. Shader

In this paper, we propose algorithms for the graph isomorphism (GI) problem that are based on the eigendecompositions of the adjacency matrices. The eigenvalues of isomorphic graphs are identical. However, two graphs $ G_A $ and $ G_B $ can…

Discrete Mathematics · Computer Science 2019-08-14 Stefan Klus , Tuhin Sahai

In a signed graph $G$, an induced subgraph is called a negative clique if it is a complete graph and all of its edges are negative. In this paper, we give the characteristic polynomials and the eigenvalues of some signed graphs having…

Discrete Mathematics · Computer Science 2018-06-01 Ranveer Singh , Ravindra B. Bapat

Symplectic geometry plays an increasingly important role in mathematics, physics and applications, and naturally gives rise to interesting matrix families and properties. One of these is the notion of symplectic eigenvalues, whose existence…

Combinatorics · Mathematics 2026-01-21 Himanshu Gupta , Leslie Hogben , Bryan Shader , Tony Wong

Associated to a graph $G$ is a set $\mathcal{S}(G)$ of all real-valued symmetric matrices whose off-diagonal entries are nonzero precisely when the corresponding vertices of the graph are adjacent, and the diagonal entries are free to be…

Spectral Theory · Mathematics 2020-11-03 Mohammad Adm , Shaun Fallat , Karen Meagher , Shahla Nasserasr , Sarah Plosker , Boting Yang

The study of solving the inverse eigenvalue problem for nonnegative matrices has been around for decades. It is clear that an inverse eigenvalue problem is trivial if the desirable matrix is not restricted to a certain structure. Provided…

Numerical Analysis · Mathematics 2014-08-13 Matthew M. Lin

In the broad range of studies related to quantum graphs, quantum graph spectra appear as a topic of special interest. They are important in the context of diffusion type problems posed on metric graphs. Theoretical findings suggest that…

Numerical Analysis · Mathematics 2023-12-15 Chong-Son Dröge , Anna Weller

The inverse eigenvalue problem of a graph $G$ studies the possible spectra of matrices associated with $G$, including as an important subproblem the possible nullities of such a matrix. Much research in this area to date has focused only on…

Combinatorics · Mathematics 2026-03-03 Aida Abiad , Mary Flagg , H. Tracy Hall , Jephian C. -H. Lin , Bryan Shader

Let G be an undirected graph on n vertices and let S(G) be the set of all real symmetric n x n matrices whose nonzero off-diagonal entries occur in exactly the positions corresponding to the edges of G. The inverse inertia problem for G…

Combinatorics · Mathematics 2007-11-21 Wayne Barrett , H. Tracy Hall , Raphael Loewy

An important facet of the inverse eigenvalue problem for graphs is to determine the minimum number of distinct eigenvalues of a particular graph. We resolve this question for the join of a connected graph with a path. We then focus on…

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