On 2×2 operator matrices
Sungeun Jung, Yoenha Kim, Eungil Ko · Operators and Matrices · 2011
In this paper, we show that some 2 2 operator matrices have scalar extensions. In particular, we focus on some 2-hyponormal operators and their generalizations. As a corollary, we get that such operator matrices have nontrivial invariant subspaces if their spectra have nonempty interiors in the complex plane.