Wielandt's theorem, spectral sets and Banach algebras

作者：Pereira Rajesh^*; Rush Stephen

来源：Linear Algebra and Its Applications, 2013, 439(4): 852-855.

DOI：10.1016/j.laa.2012.06.019

• Banach algebras
• Spectral sets
• Spectral inclusion regions
• Normal matrices
• Von Neumann operators

Let A be a complex unital Banach algebra and let a, b is an element of A. We give regions of the complex plane which contain the spectrum of a + b or ab using von Neumann spectral set theory. These results are a direct generalization of a theorem of Wielandt on the eigenvalues of the sum of two normal matrices.

• 出版日期2013-8-15