On rational and periodic solutions of stationary KdV equations.
On sampling expansions of Kramer type.
On the differential operators with periodic matrix coefficients.
On the periodic spectrum of the 1-dimensional Schrödinger operator.
On the singular spectrum of discrete Schrödinger operator
On the spectra of non-selfadjoint differential operators and their adjoints in direct sum spaces.
On the spectrum of a discrete non-Hermitian quantum system.
Optimization of the principal eigenvalue of the one-dimensional Schrödinger operator.
Oscillation theory for a pair of second order dynamic equations with a singular interface.
Perturbation of an eigen-value from a dense point spectrum : a general Floquet hamiltonian
Points tournants et résonances de Stark-Wannier
Positive solutions and nonlinear eigenvalue problems for retarded second order differential equations.
Positive solutions of two-point right focal eigenvalue problems on time scales.
Properties of eigenfunctions of non-local operators
Rayleigh principle for linear Hamiltonian systems without controllability∗
In this paper we consider linear Hamiltonian differential systems without the controllability (or normality) assumption. We prove the Rayleigh principle for these systems with Dirichlet boundary conditions, which provides a variational characterization of the finite eigenvalues of the associated self-adjoint eigenvalue problem. This result generalizes the traditional Rayleigh principle to possibly abnormal linear Hamiltonian systems. The main tools...
Rayleigh principle for linear Hamiltonian systems without controllability∗
In this paper we consider linear Hamiltonian differential systems without the controllability (or normality) assumption. We prove the Rayleigh principle for these systems with Dirichlet boundary conditions, which provides a variational characterization of the finite eigenvalues of the associated self-adjoint eigenvalue problem. This result generalizes the traditional Rayleigh principle to possibly abnormal linear Hamiltonian systems. The main tools...
Reducibility and point spectrum for linear quasi-periodic skew-products.
Regularized trace of the Sturm-Liouville operator with irregular boundary conditions.
Relative boundedness and compactness theory for second-order differential operators.
Renormalization of exponential sums and matrix cocycles
In this paper, we present a new point of view on the renormalization of some exponential sums stemming from number theory. We generalize this renormalization procedure to study some matrix cocycles arising in spectral problems of quantum mechanics