Estimation du reste dans la théorie spectrale d'une classe de problèmes d'opérateur elliptiques dégénérés
Estimations de l'effet tunnel pour le double puits. II : états hautement excités
Étude spectrale du système différentiel associé à un problème d’élasticité linéaire
Existence and perturbation of principal eigenvalues for a periodic-parabolic problem.
Existence of a principal eigenvalue for the Tricomi problem.
Existence of multiple principal eigenvalues for some indefinite linear eigenvalue problems
We study the existence of principal eigenvalues for differential operators of second order which are not necessarily in divergence form. We obtain results concerning multiplicity of principal eigenvalues in both the variational and the general case. Our approach uses systematically the Krein-Rutman theorem and fixed point arguments for the spectral radius of some associated problems. We also use a variational characterization for both the self-adjoint and the general case.
Existence of Rayleigh resonances exponentially close to the real axis
Existence of solutions for some nonlinear elliptic equations.