Let G be a connected graph with least eigenvalue −2, of multiplicity k. A star complement for −2 in G is an induced subgraph H = G − X such that |X | = k and −2 is not an eigenvalue of H . In the case that G is a generalized line graph, a characterization of such subgraphs is used to decribe the eigenspace of −2. In some instances, G itself can be characterized by a star complement. If G is not...

Two results dealing with the relation between the smallest eigenvalue of a graph and its bipartite subgraphs are obtained. The first result is that the smallest eigenvalue μ of any non-bipartite graph on n vertices with diameter D and maximum degree ∆ satisfies μ > −∆ + 1 (D+1)n . This improves previous estimates and is tight up to a constant factor. The second result is the determination of th...

In this paper, we consider the tensor generalized eigenvalue complementarity problem (TGEiCP), which is an interesting generalization of matrix eigenvalue complementarity problem (EiCP). First, we give an affirmative result showing that TGEiCP is solvable and has at least one solution under some reasonable assumptions. Then, we introduce two optimization reformulations of TGEiCP, thereby benefi...

A graph G with convex-QP stability number (or simply a convex-QP graph) is a graph for which the stability number is equal to the optimal value of a convex quadratic program, say P (G). There are polynomial-time procedures to recognize convex-QP graphs, except when the graph G is adverse or contains an adverse subgraph (that is, a non complete graph, without isolated vertices, such that the lea...

Hill’s method is a means to numerically approximate spectra of linear differential operators with periodic coefficients. In this paper, we address different issues related to the convergence of Hill’s method. We show the method does not produce any spurious approximations, and that for selfadjoint operators, the method converges in a restricted sense. Furthermore, assuming convergence of an eig...

Even if both A and B are real-valued, it is likely that λ and x are complexvalued. Finding the solution of eigensystems is a fairly complicated procedure. It is at least as difficult as finding the roots of polynomials. Therefore, any numerical method for solving eigenvalue problems is expected to be iterative in nature. Algorithms for solving eigenvalue problems include the power method, subsp...

4 A defective eigenvalues is well documented to be hypersensitive to data pertur5 bations and round-off errors, making it a formidable challenge in numerical computa6 tion particularly when the matrix is known through approximate data. This paper 7 establishes a finitely bounded sensitivity of a defective eigenvalue with respect to per8 turbations that preserve the geometric multiplicity and th...

Abstract In this article, using critical point theory and variational methods, we investigate the existence of at least three solutions for a class double eigenvalue discrete anisotropic Kirchhoff-type problems. An example is presented to demonstrate applicability our main theoretical findings.

Quadratic eigenvalue problems involving large matrices arise frequently in areas such as the vibration analysis of structures, MEMS simulation, and the solution of quadratically constrained least squares problems. The typical approach is to solve the quadratic eigenvalue problem using a mathematically equivalent linearized formulation, resulting in a doubled dimension and a lack of backward sta...

*Correspondence: [email protected] 1School of Mathematics and Statistics, Yancheng Teachers University, Yancheng, Jiangsu 224002, P.R. China Full list of author information is available at the end of the article Abstract A unicyclic graph is a connected graph whose number of edges is equal to the number of vertices. Fan et al. (Discrete Math. 313:903-909, 2013) and Liu et al. (Electron. J. Linear ...