Equivalence of Boundary Eigenvalue Operator Fuctions and their Characteristic Matrix Functions.
Erratum to “Non-trapping condition for semiclassical Schrödinger operators with matrix-valued potentials”.
Essential descent spectrum and commuting compact perturbations.
Essential spectra of quasisimilar -quasihyponormal operators.
Estimates for a number of negative eigenvalues of the Schrödinger operator with intensive magnetic field
Estimations de l'effet tunnel pour le double-puits
Étude d'une fonction remarquable associée aux moyennes de convolution
Dans cet article nous étudions la série génératrice des poids alternés d’une moyenne de convolution induite par un processus de diffusion. Nous montrons que celle-ci est une fonction méromorphe, naturellement liée à un certain opérateur compact. Cette fonction est simplement égale à , lorsque le déterminant de Fredholm de cet opérateur existe, et nous la précisons dans les autres cas.
Examples of stable -semigroups
Exemples de noyaux admettant des resolvantes.
Exponential stability of linear and almost periodic systems on Banach spaces.
Exponentials of bounded normal operators
The present paper is mainly concerned with equations involving exponentials of bounded normal operators. Conditions implying commutativity of normal operators are given, without using the known 2πi-congruence-free hypothesis. This is a continuation of a recent work by the second author.
Extended Weyl type theorems
An operator acting on a Banach space possesses property if where is the approximate point spectrum of , is the essential semi-B-Fredholm spectrum of and is the set of all isolated eigenvalues of In this paper we introduce and study two new properties and in connection with Weyl type theorems, which are analogous respectively to Browder’s theorem and generalized Browder’s theorem. Among other, we prove that if is a bounded linear operator acting on a Banach space , then...
External approximation of eigenvalue problems in Banach spaces
Factorization by Lattice Homomorphisms.
Fermi Golden Rule, Feshbach Method and embedded point spectrum
A method to study the embedded point spectrum of self-adjoint operators is described. The method combines the Mourre theory and the Limiting Absorption Principle with the Feshbach Projection Method. A more complete description of this method is contained in a joint paper with V. Jakić, where it is applied to a study of embedded point spectrum of Pauli-Fierz Hamiltonians.
Feynman's operational calculi: using Cauchy's integral formula.
First results on spectrally bounded operators
A linear mapping T from a subspace E of a Banach algebra into another Banach algebra is defined to be spectrally bounded if there is a constant M ≥ 0 such that r(Tx) ≤ Mr(x) for all x ∈ E, where r(·) denotes the spectral radius. We study some basic properties of this class of operators, which are sometimes analogous to, sometimes very different from, those of bounded operators between Banach spaces.
Floquet operators without absolutely continuous spectrum
Fonction spectrale d'opérateurs non elliptiques
Formeln für Pole der Resolvente und den Radius eines wesentlichen Spektrums.