Opuscula Math. 27, no. 2 (2007), 301-304

Opuscula Mathematica

Spectra of subnormal pairs

Krzysztof Rudol

Abstract. In this short note we present an example related to joint spectra of subnormal pairs of bounded operators. A counterexample to the equality between Taylor's spectrum and the closure of the defect spectrum is given. This example is related to the author's modification of N. Sibony's counterexample to Corona Theorem on domains that fail to be strictly pseudoconvex.

Keywords: subnormal operator, corona, joint spectrum.

Mathematics Subject Classification: 47B20, 46J15.

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  • Krzysztof Rudol
  • AGH University of Science and Technology, Faculty of Applied Mathematics, al. Mickiewicza 30, 30-059 Cracow, Poland
  • Received: 2006-11-26.
Opuscula Mathematica - cover

Cite this article as:
Krzysztof Rudol, Spectra of subnormal pairs, Opuscula Math. 27, no. 2 (2007), 301-304

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