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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: 1Citation - Scopus: 1On 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.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: 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: 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: 65Citation - Scopus: 69On the Concept of Spectral Singularities(indian Acad Sciences, 2009) Guseinov, Gusein ShIn this paper, we discuss the concept of spectral singularities for non-Hermitian Hamiltonians. We exihibit spectral singularities of some well-known concrete Hamiltonians with complex-valued coefficients.Article Citation - WoS: 283Citation - Scopus: 316Integration on Time Scales(Academic Press inc Elsevier Science, 2003) Guseinov, GS; Hüseyin, Hüseyin Şirin; Hüseyin, Hüseyin Şirin; Mathematics; MathematicsIn this paper we study the process of Riemann and Lebesgue integration oil time scales. The relationship of the Riemann and Lebesgue integrals is considered and a criterion for Riemann integrability is established. (C) 2003 Elsevier Inc. All rights reserved.Article On the Functions of Two Commuting Laplace-Beltrami Operators in Hyperbolic Space(Pergamon-elsevier Science Ltd, 2014) Guseinov, Gusein ShWe describe the structure of arbitrary rapidly decreasing two-variable function of two commuting Laplace-Beltrami operators in the product of two many-dimensional hyperbolic spaces showing that the function of the commuting Laplace-Beltrami operators is an integral operator and giving an explicit formula for its kernel.Article Citation - WoS: 3Citation - Scopus: 3Description of the Structure of Arbitrary Functions of the Laplace-Beltrami Operator in Hyperbolic Space(Taylor & Francis Ltd, 2013) Guseinov, Gusein ShWe describe the structure of an arbitrary rapidly decreasing function of the Laplace-Beltrami operator in n-dimensional hyperbolic space showing that the function of the Laplace-Beltrami operator is an integral operator and giving an explicit formula for its kernel.Article Citation - WoS: 3Citation - Scopus: 3A Class of Complex Solutions To the Finite Toda Lattice(Pergamon-elsevier Science Ltd, 2013) Guseinov, Gusein Sh.In this paper, a class of complex-valued solutions to the finite Toda lattice is constructed by using the inverse spectral method. The corresponding Lax operator is a finite complex Jacobi matrix. As the initial values there are taken such complex numbers that the corresponding Jacobi matrix has a simple spectrum. Some examples are given. (C) 2012 Elsevier Ltd. All rights reserved.
