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Article Citation - WoS: 1Citation - Scopus: 3Spectral Approach To Derive the Representation Formulae for Solutions of the Wave Equation(Hindawi Publishing Corporation, 2012) Guseinov, Gusein Sh.Using spectral properties of the Laplace operator and some structural formula for rapidly decreasing functions of the Laplace operator, we offer a novel method to derive explicit formulae for solutions to the Cauchy problem for classical wave equation in arbitrary dimensions. Among them are the well-known d'Alembert, Poisson, and Kirchhoff representation formulae in low space dimensions.Article Citation - WoS: 1Citation - Scopus: 1On the Eigenfunction Expansion of the Laplace-Beltrami Operator in Hyperbolic Space(Taylor & Francis Ltd, 2015) Guseinov, Gusein Sh.We describe the spectral projection of the Laplace-Beltrami operator in n-dimensional hyperbolic space by studying its resolvent as an analytic operator-valued function and applying the technique of contour integration. As a result an integral formula is established for the associated Legendre functionArticle Citation - WoS: 10Citation - Scopus: 12On an Inverse Problem for Two Spectra of Finite Jacobi Matrices(Elsevier Science inc, 2012) Guseinov, Gusein Sh.We solve a version of the inverse spectral problem for two spectra of finite order real Jacobi matrices. The problem is to reconstruct the matrix using two sets of eigenvalues, one for the original Jacobi matrix and one for the matrix obtained by replacing the last diagonal element of the Jacobi matrix by some another number. The uniqueness and existence results for solution of the inverse problem are established and an explicit procedure of reconstruction of the matrix from the two spectra is given. (C) 2012 Elsevier Inc. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7On the Impulsive Boundary Value Problems for Nonlinear Hamiltonian Systems(Wiley, 2016) Guseinov, Gusein Sh.In this work, we deal with two-point boundary value problems for nonlinear impulsive Hamiltonian systems with sub-linear or linear growth. A theorem based on the Schauder fixed point theorem is established, which gives a result that yields existence of solutions without implications that solutions must be unique. An upper bound for the solution is also established. Examples are given to illustrate the main result. Copyright (C) 2016 John Wiley & Sons, Ltd.Article Citation - WoS: 1Citation - Scopus: 1Spectral Method for Deriving Multivariate Poisson Summation Formulae(Amer inst Mathematical Sciences-aims, 2013) Guseinov, Gusein Sh.We show that using spectral theory of a finite family of pair-wise commuting Laplace operators and the spectral properties of the periodic Laplace operator some analogues of the classical multivariate Poisson summation formula can be derived.Conference Object Inverse Spectral Problems for Complex Jacobi Matrices(Springer New York LLC, 2013) Guseinov,G.S.The paper deals with two versions of the inverse spectral problem for finite complex Jacobi matrices. The first is to reconstruct the matrix using the eigenvalues and normalizing numbers (spectral data) of the matrix. The second is to reconstruct the matrix using two sets of eigenvalues (two spectra), one for the original Jacobi matrix and one for the matrix obtained by deleting the last row and last column of the Jacobi matrix. Uuniqueness and existence results for solution of the inverse problems are established and an explicit procedure of reconstruction of the matrix from the spectral data is given. It is shown how the results can be used to solve finite Toda lattices subject to the complex-valued initial conditions. © Springer Science+Business Media New York 2013.Article Citation - WoS: 1Citation - Scopus: 1An Application of Spectral Theory of the Laplace Operator(Taylor & Francis Ltd, 2013) Guseinov, Gusein Sh.We describe the structure of arbitrary rapidly decreasing functions of the Laplace operator. Combining this with the spectral data of the periodic Laplace operator we develop a generalization of the classical Poisson summation formula.Article Citation - WoS: 15Citation - Scopus: 18Inverse Spectral Problems for Tridiagonal N by N Complex Hamiltonians(Natl Acad Sci Ukraine, inst Math, 2009) Guseinov, Gusein Sh.In this paper, the concept of generalized spectral function is introduced for finite-order tridiagonal symmetric matrices (Jacobi matrices) with complex entries. The structure of the generalized spectral function is described in terms of spectral data consisting of the eigenvalues and normalizing numbers of the matrix. The inverse problems from generalized spectral function as well as from spectral data are investigated. In this way, a procedure for construction of complex tridiagonal matrices having real eigenvalues is obtained.Article Citation - WoS: 3Citation - Scopus: 3An Inverse Spectral Problem for Complex Jacobi Matrices(Elsevier, 2010) Guseinov, Gusein Sh.We introduce the concept of generalized spectral function for finite order complex Jacobi matrices and solve the inverse problem with respect to the generalized spectral function. The results obtained can be used for solving of initial-boundary value problems for finite nonlinear Toda lattices with the complex-valued initial conditions by means of the inverse spectral problem method. (C) 2009 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 4On a Discrete Inverse Problem for Two Spectra(Hindawi Ltd, 2012) Guseinov, Gusein Sh.A version of the inverse spectral problem for two spectra of finite-order real Jacobi matrices (tridiagonal symmetric matrices) is investigated. The problem is to reconstruct the matrix using two sets of eigenvalues: one for the original Jacobi matrix and one for the matrix obtained by deleting the last row and last column of the Jacobi matrix.
