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Multiplication and composition operators on the derivative Hardy space S2(\mathbbD)

2018/08/29 by Gu, Caixing, Luo, Shuaibing
#FOS: Mathematics #Functional Analysis (math.FA)

paper · doi:10.48550/arxiv.1808.10041

Abstract

In this paper we propose a different (and equivalent) norm on S2 (\mathbbD) which consists of functions whose derivatives are in the Hardy space of unit disk. The reproducing kernel of S2(\mathbbD) in this norm admits an explicit form, and it is a complete Nevanlinna-Pick kernel. Furthermore, there is a surprising connection of this norm with 3 -isometries. We then study composition and multiplication operators on this space. Specifically, we obtain an upper bound for the norm of Cφ for a class of composition operators. We completely characterize multiplication operators which are m-isometries. As an application of the 3-isometry, we describe the reducing subspaces of Mφ on S2(\mathbbD) when φ is a finite Blaschke product of order 2.

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