Abstract
Anderson's theorem states that if the numerical range W(A) of an n-by-n matrix A is contained in the unit disk D‾ and intersects with the unit circle at more than n points, then W(A)=D‾. An analogue of this result for compact A in an infinite dimensional setting was established by Gau and Wu. We consider here the case of A being the sum of a normal and compact operator.
Original language | English (US) |
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Pages (from-to) | 349-353 |
Number of pages | 5 |
Journal | Journal of Mathematical Analysis and Applications |
Volume | 461 |
Issue number | 1 |
DOIs | |
State | Published - May 1 2018 |
Keywords
- Compact operator
- Normal operator
- Numerical range
- Weighted shift
ASJC Scopus subject areas
- Analysis
- Applied Mathematics