2024-03-29T13:36:27Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/688912022-11-17T02:08:08Zhdl_2115_45007hdl_2115_116Hyponormal Toeplitz operators and extremal problems of Hardy spacesNakazi, TakahikoTakahashi, Katsutoshiopen access410The 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 the Halmos's question about a subnormal Toeplitz operator when the selfcornmutator is finite rank.Department of Mathematics, Hokkaido University1992-04engdepartmental bulletin paperVoRhttps://doi.org/10.14943/83289http://hdl.handle.net/2115/6889110.14943/83289Hokkaido University Preprint Series in Mathematics145230https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/68891/1/pre145.pdfapplication/pdf870.38 KB1992-04