Abstract
By considering various functions of the Volterra operator $V$, examples are obtained to show that (i) similar contractions need not have the same defect numbers, (ii) unicellular operators may have large spectra, and (iii) the disk $|z| \leqq ||T||$ need not be a minimal spectral set for an operator $T$ of the form 1 + compact. A complete description is also given of those disks that are a spectral set for some conjugate of $V$.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
