The role of zero sets in the spectra of hyponormal operators

The role of zero sets in the spectra of hyponormal operators
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by C. R. Putnam

Proc. Amer. Math. Soc. 43 (1974), 137-140

DOI: https://doi.org/10.1090/S0002-9939-1974-0333808-6

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A compact set in the complex plane is the spectrum of a completely hyponormal operator if and only if the set has positive density.

References

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