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In this paper following the same methods in [M. Kadakal, O. Sh. Mukhtarov, Sturm-Liouville problems with discontinuities at two points, Comput. Math. Appl., 54 (2007) 1367-1379] we investigate discontinuous two-point boundary value problems…

Classical Analysis and ODEs · Mathematics 2013-04-23 Erdoğan Şen , Oktay Mukhtarov

Non-smoothness at optimal points is a common phenomenon in many eigenvalue optimization problems. We consider two recent algorithms to minimize the largest eigenvalue of a Hermitian matrix dependent on one parameter, both proven to be…

Numerical Analysis · Mathematics 2018-05-14 Fatih Kangal , Emre Mengi

In the mathematical problem of linear hydrodynamic stability for shear flows against Tollmien-Schlichting perturbations, the continuity equation for the perturbation of the velocity is replaced by a Poisson equation for the pressure…

Numerical Analysis · Mathematics 2024-09-17 Cătălin Liviu Bichir , Adelina Georgescu

We study the existence of positive eigenvalues with associated nonnegative mild eigenfunctions for a class of abstract initial value problems in Banach spaces with functional, possibly nonlocal, initial conditions. The framework includes…

Classical Analysis and ODEs · Mathematics 2026-01-01 Gennaro Infante , Paola Rubbioni

This work is concerned with the existence and uniqueness of boundary value problems defined on semi-infinite intervals. These kinds of problems seldom admit exactly known solutions and, therefore, the theoretical information on their…

Numerical Analysis · Mathematics 2020-11-17 Riccardo Fazio

We study the optimal partitioning of a (possibly unbounded) interval of the real line into $n$ subintervals in order to minimize the maximum of certain set-functions, under rather general assumptions such as continuity, monotonicity, and a…

Optimization and Control · Mathematics 2019-05-08 Paolo Tilli , Davide Zucco

Error estimates for approximations of harmonic functions on planar regions by subspaces spanned by the first harmonic Steklov eigenfunctions are found. They are based on the explicit representation of harmonic functions in terms of these…

Analysis of PDEs · Mathematics 2016-09-26 Giles Auchmuty , Manki Cho

Many physical systems can be described by nonlinear eigenvalues and bifurcation problems with a linear part that is non-selfadjoint e.g. due to the presence of loss and gain. The balance of these effects is reflected in an antilinear…

Mathematical Physics · Physics 2015-04-30 Tomas Dohnal , Petr Siegl

This paper is concerned with eigenvalue problems for non-symmetric elliptic operators with large drifts in bounded domains under Dirichlet boundary conditions. We consider the minimal principal eigenvalue and the related principal…

Analysis of PDEs · Mathematics 2017-10-16 Francois Hamel , Luca Rossi , Emmanuel Russ

In this paper we consider a class of planar autonomous systems having an isolated limit cycle x_0 of smallest period T>0 such that the associated linearized system around it has only one characteristic multiplier with absolute value 1. We…

Classical Analysis and ODEs · Mathematics 2007-09-28 Oleg Makarenkov , Paolo Nistri

In this paper we study a family of operators dependent on a small parameter $\epsilon > 0$, which arise in a problem in fluid mechanics. We show that the spectra of these operators converge to N as $\epsilon \to 0$, even though, for fixed…

Spectral Theory · Mathematics 2014-02-26 E. B. Davies , John Weir

We consider a perturbation problem for embedded eigenvalues of a self-adjoint differential operator in $L^2(\mathbb R;\mathbb R^n)$. In particular, we study the set of all small perturbations in an appropriate Banach space for which the…

Functional Analysis · Mathematics 2021-06-08 Sara Maad Sasane , Alexia Papalazarou

The maximum (or minimum) generalized eigenvalue of symmetric positive semidefinite matrices that depend on optimization variables often appears as objective or constraint functions in structural topology optimization when we consider…

Optimization and Control · Mathematics 2024-05-09 Akatsuki Nishioka , Yoshihiro Kanno

The present paper gives a priori bounds on the possible non-real eigenvalues of regular indefinite Sturm-Liouville problems and obtains sufficient conditions for such problems to admit non-real eigenvalues.

Spectral Theory · Mathematics 2013-06-25 Jiangang Qi , Shaozhu Chen

A new continuity for set-valued functions is introduced, and an existence theorem is proved for such continuous set-valued functions.

Numerical Analysis · Mathematics 2009-01-13 Alexandre Goldsztejn

The central problem we consider is the distribution of eigenvalues of closed linear operators which are not selfadjoint, with a focus on those operators which are obtained as perturbations of selfadjoint linear operators. Two methods are…

Spectral Theory · Mathematics 2014-03-25 Michael Demuth , Marcel Hansmann , Guy Katriel

This article addresses structure-preserving smooth approximation of semiconcave functions. semiconcave functions are of particular interest because they naturally arise in a variety of variational problems, including {optimal feedback…

Optimization and Control · Mathematics 2026-02-10 Karl Kunisch , Donato Vásquez-Varas

A very simple unidimensional function with Lipschitz continuous gradient is constructed such that the ADAM algorithm with constant stepsize, started from the origin, diverges when applied to minimize this function in the absence of noise on…

Machine Learning · Computer Science 2023-08-03 Ph. L. Toint

We consider boundary value problems for stochastic differential equations of second order with a small parameter. For this case we prove a special existence and unicity theorem for strong solutions. The asymptotic behavior of these…

Probability · Mathematics 2015-07-08 Mikhail Kamenskii , Marc Quincampoix , Serguei Pergamenchtchikov

Many results in the theory of Gaussian processes rely on the eigenstructure of the covariance operator. However, eigenproblems are notoriously hard to solve explicitly and closed form solutions are known only in a limited number of cases.…

Probability · Mathematics 2018-05-23 Pavel Chigansky , Marina Kleptsyna