Title

Projections as averages of isometries on minimal norm ideals

Abstract

In this paper, we consider projections on minimal norm ideals of B(H) that are represented as the average of two surjective isometries. We describe projections of the formP(T)= A1 TB 1+ A 2TB2/2,where A1, A2, B1 and B2 are unitary operators satisfying a commutativity condition. We also characterize classes of projections of the formP(T)=AT+T tB/2andP(T)= ATt+TtB/2,with A and B unitary operators satisfying a spectral condition. © 2011 Published by Elsevier Inc.

Publication Title

Linear Algebra and Its Applications

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