2021-12-08T01:42:30Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/692122018-04-25T23:44:07Zhdl_2115_45007hdl_2115_116Essential norms of some singular integral operatorsNakazi, T.Singular integral operatoressential norm410Let o: and /3 be bounded measurable functions on the unit circle T. The singular integral operator Sa.,() is defined by Sa.,rd = o:P f + /3Qf (f E L2 (T)) where P is an analytic projection and Q is a co-analytic projection. In the previous paper, the norm of Sa.,() was calculated in general, using o:, /3 and o:fJ + H00 where H00 is a Hardy space in L00 (T). In this pa.per, the essential norm JJSa.,(Jlle of Sa.,() is calculated in general, using o:fJ + H00 + C where C is a set of all continuous functions on T. Hence if o:fJ is in H∞ + C then IISa.,(Jlle = max(llo:Jl00, Jl/31100). This gives a known result when o:, /3 are in C.Departmental Bulletin Paperapplication/pdfhttp://hdl.handle.net/2115/69212info:doi/10.14943/83608https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/69212/1/pre462.pdfHokkaido University Preprint Series in Mathematics462161999-06-01engpublisher