The main focus of this book is on bounded linear operators on complex infinitedimensional
Banach spaces and their spectral properties. In recent years spectral theory, which has …

Let X and Y be Banach spaces. When A and B are linear relations in X and Y, respectively,
we denote by MC the linear relation in X× Y of the form M_c=\Big (A & C\0 & B) M c=(AC 0 …

In\cite {koliha}, Koliha proved that $ T\in L (X) $($ X $ is a complex Banach space) is
generalized Drazin invertible operator equivalent to there exists an operator $ S …

Given a Banach space operator T∈ B (χ), the following statements are equivalent:(i) T is
polynomially meromorphic;(ii) T is generalised meromorphic;(iii) f (T) is meromorphic for …

Let T be a bounded linear operator on a Banach space X, and let M be a closed T-invariant
subspace of X. In this paper, we investigate the relationships between the Drazin spectrum …

Three-space theorem for semi-Fredholmness Page 1 Arch. Math. 100 (2013), 55–61 c© 2012
Springer Basel 0003-889X/13/010055-7 published online December 27, 2012 DOI …

When $ A\in\mathcal B (H) $ and $ B\in\mathcal B (K) $ are given, we denote by $ M_C $ the
operator on the Hilbert space $ H\oplus K $ of the form $ M_C=\left (\begin {array}{ccc} A & …

Let be a 2-by-2 upper triangular operator matrix acting on the Banach space or Hilbert
space. For the most important spectra such as spectrum, essential spectrum and Weyl …

THE RECONSTRUCTION PROBLEM FOR A MULTIVALUED LINEAR OPERATOR’S
PROPERTIES 1. Introduction Let X be a complex Banach space, M i Page 1 Revista de la …

Abstract When A∈ B (H) and B∈ B (K) are given, we denote by MC the operator on the
Hilbert space H ⊕ K of the form MC=(AC 0 B). In this paper we investigate the quasi …