P-adic semi-Fredholm operators and measures of non-compactness.
Perturbation Classes of Semi-Fredholm Operators.
Perturbation of a Fredholm complex by inessential operators.
Perturbation results on semi-Fredholm operators and applications.
Perturbation theory and strictly singular operators in locally convex spaces
Perturbation theory relative to a Banach algebra of operators
Let ℬ be a Banach algebra of bounded linear operators on a Banach space X. Let S be a closed linear operator in X, and let R be a linear operator in X. In this paper the spectral and Fredholm theory relative to ℬ of the perturbed operator S + R is developed. In particular, the situation where R is S-inessential relative to ℬ is studied. Several examples are given to illustrate the usefulness of these concepts.
Perturbations of Fredholm operators
Polaroid type operators and compact perturbations
A bounded linear operator T acting on a Hilbert space is said to be polaroid if each isolated point in the spectrum is a pole of the resolvent of T. There are several generalizations of the polaroid property. We investigate compact perturbations of polaroid type operators. We prove that, given an operator T and ε > 0, there exists a compact operator K with ||K|| < ε such that T + K is polaroid. Moreover, we characterize those operators for which a certain polaroid type property is stable under...
Polaroid type operators under perturbations
A bounded operator T defined on a Banach space is said to be polaroid if every isolated point of the spectrum is a pole of the resolvent. The "polaroid" condition is related to the conditions of being left polaroid, right polaroid, or a-polaroid. In this paper we explore all these conditions under commuting perturbations K. As a consequence, we give a general framework from which we obtain, and also extend, recent results concerning Weyl type theorems (generalized or not) for T + K, where K is an...
Projektoren und relative Inversion holomorpher Semi-Fredholmfunktionen.
Properness and topological degree for general elliptic operators.
Properness and topological degree for nonlocal reaction-diffusion operators.
Properties of Some Norm Related Functions of Unbounded Linear Operators.
Property (gz) for bounded linear operators