Hyponormality of Toeplitz Operators on the Dirichlet Space
Received:June 01, 2010  Revised:January 12, 2011
Key Words: Toeplitz operator   hyponormality   Dirichlet space   harmonic Dirichlet space.  
Fund Project:Supported by the National Natural Science Foundation of China (Grant No.10971195) and the Natural Science Foundation of Zhejiang Province (Grant Nos.Y6090689; Y6110260).
Author NameAffiliation
Qiao Fei LU Department of Mathematics, Zhejiang Normal University, Zhejiang 321004, P. R. China 
Tao YU Department of Mathematics, Zhejiang Normal University, Zhejiang 321004, P. R. China 
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Abstract:
      In this paper, we prove that the necessary and sufficient condition for a Toeplitz operator $T_u$ on the Dirichlet space to be hyponormal is that the symbol $u$ is constant for the case that the projection of $u$ in the Dirichlet space is a polynomial and for the case that $u$ is a class of special symbols, respectively. We also prove that a Toeplitz operator with harmonic polynomial symbol on the harmonic Dirichlet space is hyponormal if and only if its symbol is constant.
Citation:
DOI:10.3770/j.issn:1000-341X.2011.06.013
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