Spectrum and essential spectrum of Toeplitz operators
Dechao Zheng (Vanderbilt University & Chongqing University)
9:30 am to 10:30 am, August 8th, 2012 Science Building A1510
Abstract:
On the Hardy space, by means of an elegant and ingenious argument, Widom showed that the spectrum of a bounded Toeplitz operator is always connected and Douglas showed that the essential spectrum of a bounded Toeplitz operator is also connected. On the Bergman space, in 1979, G. McDonald and the C. Sundberg showed that the essential spectrum of T' is connected
for ' a harmonic function on the unit disk which is either real or piecewise continuous on the boundary. They asked whether the essential spectrum of a Toeplitz operator on the Bergman space with bounded harmonic symbol is connected.
In this talk, we will show an example that the spectrum and the essential spectrum of a Toeplitz operator with bounded harmonic symbol is disconnected.
This is a joint work with Carl Sundberg.
In this talk, we will show an example that the spectrum and the essential spectrum of a Toeplitz operator with bounded harmonic symbol is disconnected.
This is a joint work with Carl Sundberg.
About the speaker:
郑德超教授是国际著名数学家，函数空间上的算子理论研究领域的领军人物。郑德超教授现任重庆大学两江数学中心主任，博士生导师。
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