Fredholm Theory Relative to a Banach Algebra Homomorphism.
Fredholmness of pseudo-differential operators with nonregular symbols
We establish the Fredholmness of a pseudo-differential operator whose symbol is of class , , in the spatial variable. Our work here refines the work of H. Abels, C. Pfeuffer (2020).
Fredholmspektren verbundener Operatoren.
Gap and perturbation of non-semi-Fredholm operators.
Generalization of formulae of Fredholm type
Generalized a-Weyl's theorem and the single-valued extension property.
Let T be a bounded linear operator acting on a Banach space X such that T or T* has the single-valued extension property (SVEP). We prove that the spectral mapping theorem holds for the semi-essential approximate point spectrum σSBF-+(T); and we show that generalized a-Browder's theorem holds for f(T) for every analytic function f defined on an open neighbourhood U of σ(T): Moreover, we give a necessary and sufficient condition for such T to obey generalized a-Weyl's theorem. An application is given...
Generalized a-Weyl's theorem for direct sums
Generalized fractional linear transformations: convexity and compactness of the image and the pre-image; applications.
The convexity and compactness in the weak operator topology of the image and pre-image of a generalized fractional linear transformation is established. As an application the exponential dichotomy of solutions to evolution problems of the parabolic type is proved.
Generalized Weyl's theorem and quasi-affinity
A bounded operator T ∈ L(X) acting on a Banach space X is said to satisfy generalized Weyl's theorem if the complement in the spectrum of the B-Weyl spectrum is the set of all eigenvalues which are isolated points of the spectrum. We prove that generalized Weyl's theorem holds for several classes of operators, extending previous results of Istrăţescu and Curto-Han. We also consider the preservation of generalized Weyl's theorem between two operators T ∈ L(X), S ∈ L(Y) intertwined or asymptotically...
Generating real maps on a biordered set.
Generating real maps on a biordered set
Several authors have defined operational quantities derived from the norm of an operator between Banach spaces. This situation is generalized in this paper and we present a general framework in which we derivate several maps from an initial one , where is a set endowed with two orders, and , related by certain conditions. We obtain only three different derivated maps, if the initial map is bounded and monotone.
Generic properties of von Kármán equations
Geometric characteristic of semi-Fredholm operators and their asymptotic behaviour
Hamiltonien périodique de surface : désintégration de Floquet
Holomorphe Störungstheorie in lokalkonvexen Räumen.
Holomorphic Relative Inverses of Operator Valued Functions.
Hypercyclic sequences of operators
A sequence (Tₙ) of bounded linear operators between Banach spaces X,Y is said to be hypercyclic if there exists a vector x ∈ X such that the orbit Tₙx is dense in Y. The paper gives a survey of various conditions that imply the hypercyclicity of (Tₙ) and studies relations among them. The particular case of X = Y and mutually commuting operators Tₙ is analyzed. This includes the most interesting cases (Tⁿ) and (λₙTⁿ) where T is a fixed operator and λₙ are complex numbers. We also study when a sequence...
Index theory for multivariable Wiener-Hopf operators.
Inessential operators and incomparability of Banach spaces.
We obtain several characterizations for the classes of Riesz and inessential operators, and apply them to extend the family of Banach spaces for which the essential incomparability class is known, solving partially a problem posed in [6].
Invariance of the Fredholm radius of the Neumann operator