Hyponormal Toeplitz operators and extremal problems of Hardy spaces

Nakazi, Takahiko; Takahashi, Katsutoshi

doi:10.1090/S0002-9947-1993-1162103-7

Hyponormal Toeplitz operators and extremal problems of Hardy spaces
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by Takahiko Nakazi and Katsutoshi Takahashi

Trans. Amer. Math. Soc. 338 (1993), 753-767

DOI: https://doi.org/10.1090/S0002-9947-1993-1162103-7

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Abstract:

The symbols of hyponormal Toeplitz operators are completely described and those are also studied, being related with the extremal problems of Hardy spaces. Moreover, we discuss Halmos’s question about a subnormal Toeplitz operator when the self-commutator is finite rank.

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