Anderson's theorem for compact operators

Hwa Long Gau, Pei Yuan Wu

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


It is shown that if A is a compact operator on a Hilbert space with its numerical range W(A) contained in the closed unit disc double-struck D sign̄ and with W(A) intersecting the unit circle at infinitely many points, then W(A) is equal to double-struck D sign̄. This is an infinite-dimensional analogue of a result of Anderson for finite matrices.

Original languageEnglish
Pages (from-to)3159-3162
Number of pages4
JournalProceedings of the American Mathematical Society
Issue number11
StatePublished - Nov 2006


  • Compact operator
  • Numerical range


Dive into the research topics of 'Anderson's theorem for compact operators'. Together they form a unique fingerprint.

Cite this