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Acta Mathematica Vietnamica

Upper Triangular Operator Matrices, SVEP, and Property (w)

icon-email Mohammad H. M. Rashid

Abstract

When AL(X) and BL(Y) are given, we denote by MC an operator acting on the Banach space XY of the form MC=(AC0B). In this paper, first we prove that σw(M0)=σw(MC){S(A)S(B)} and σaw(MC)σaw(M0)S+(A)S+(B). Also, we give the necessary and sufficient condition for MC to be obeys property (w). Moreover, we explore how property (w) survive for 2×2 upper triangular operator matrices MC. In fact, we prove that if A is polaroid on E0(MC)={λisoσ(MC):0<dim(MCλ)1}, M0 satisfies property (w), and A and B satisfy either the hypotheses (i) A has SVEP at points λσaw(M0)σSF+(A) and A has SVEP at points μσw(M0)σSF+(A), or (ii) A has SVEP at points λσw(M0)σSF+(A) and B has SVEP at points μσw(M0)σSF+(B), then MC satisfies property (w). Here, the hypothesis that points λE0(MC) are poles of A is essential. We prove also that if S(A)S(B), points λEa0(MC) are poles of A and points μEa0(B) are poles of B, then MC satisfies property (w). Also, we give an example to illustrate our results.