The generalized Brauer–Ostrowski theorem for matrices of operators
Yaru Qi, Huanhuan Yang · Linear and Multilinear Algebra · 2022
The classical Brauer–Ostrowski Theorem and the Ostrowski Theorem give spectral enclosures of matrices by a union of Cassini ovals and a union of some disks, respectively. In this paper, we obtain the corresponding results for operator matrices.