The effect of variational framework on the spectral asymptotics for nonlinear elliptic two-parameter problems
The eigenvalue problem with conductivity boundary conditions
The error estimates for the infinite element method for eigenvalue problems
The essential spectrum of relativistic multi-particle operators
The gaps in the spectrum of the Schrödinger operator
We obtain inequalities between the eigenvalues of the Schrödinger operator on a compact domain Ω of a submanifold M in with boundary ∂Ω, which generalize many existing inequalities for the Laplacian on a bounded domain of a Euclidean space. We also establish similar inequalities for a closed minimal submanifold in the unit sphere, which generalize and improve Yang-Yau’s result.
The integral equation methods for the perturbed Helmholtz eigenvalue problems.
The periodic parabolic eigenvalue problem with L... weight.
The principal spectrum for linear nonautonomous parabolic PDEs of second order: Space-independent case
We show that the study of the principal spectrum of a linear nonautonomous parabolic PDE of second order on a bounded domain, with the Dirichlet or Neumann boundary conditions, reduces to the investigation of the spectrum of the linear nonautonomous ODE v̇ = a(t)v.
The pseudo--Laplace eigenvalue problem and viscosity solutions as
We consider the pseudo--laplacian, an anisotropic version of the -laplacian operator for . We study relevant properties of its first eigenfunction for finite and the limit problem as .
The pseudo-p-Laplace eigenvalue problem and viscosity solutions as p → ∞
We consider the pseudo-p-Laplacian, an anisotropic version of the p-Laplacian operator for . We study relevant properties of its first eigenfunction for finite p and the limit problem as p → ∞.
The speed of propagation for KPP type problems. I: Periodic framework
This paper is devoted to some nonlinear propagation phenomena in periodic and more general domains, for reaction-diffusion equations with Kolmogorov–Petrovsky–Piskunov (KPP) type nonlinearities. The case of periodic domains with periodic underlying excitable media is a follow-up of the article [7]. It is proved that the minimal speed of pulsating fronts is given by a variational formula involving linear eigenvalue problems. Some consequences concerning the influence of the geometry of the domain,...
Théorie spectrale d'opérateurs elliptiques sur des ouverts irréguliers
Tunnel effect and symmetries for non-selfadjoint operators
We study low lying eigenvalues for non-selfadjoint semiclassical differential operators, where symmetries play an important role. In the case of the Kramers-Fokker-Planck operator, we show how the presence of certain supersymmetric and -symmetric structures leads to precise results concerning the reality and the size of the exponentially small eigenvalues in the semiclassical (here the low temperature) limit. This analysis also applies sometimes to chains of oscillators coupled to two heat baths,...
Tunnel effect for semiclassical random walk
In this note we describe recent results on semiclassical random walk associated to a probability density which may also concentrate as the semiclassical parameter goes to zero. The main result gives a spectral asymptotics of the close to eigenvalues. This problem was studied in [1] and relies on a general factorization result for pseudo-differential operators. In this note we just sketch the proof of this second theorem. At the end of the note, using the factorization, we give a new proof of the...
Two-sided bounds of eigenvalues of second- and fourth-order elliptic operators
This article presents an idea in the finite element methods (FEMs) for obtaining two-sided bounds of exact eigenvalues. This approach is based on the combination of nonconforming methods giving lower bounds of the eigenvalues and a postprocessing technique using conforming finite elements. Our results hold for the second and fourth-order problems defined on two-dimensional domains. First, we list analytic and experimental results concerning triangular and rectangular nonconforming elements which...
Über das Fehlen positiver Eigenwerte bei einer Klasse elliptischer Differential|operatoren.
Über den ersten Eigenwert des Laplace-Operators auf kompakten Riemannschen Flächen
Über die Länge der Knotenlinien schwingender Membranen.
Über Verallgemeinerungen des Virialsatzes und Existenzfragen von Eigenwerten bei Schrödingeroperatoren
Un majorant du nombre des valeurs propres négatives correspondantes à l’opérateur de Schrödinger généralisé.
On donne une borne supérieur du nombre des valeurs propres négatives de l’opérateur de Schrödinger généralisé, cette borne est donnée en fonction d’un nombre fini de cube dyadiques minimaux.