This book presents a wide panorama of methods to investigate the spectral properties of
block operator matrices. Particular emphasis is placed on classes of block operator matrices …

In this paper a new concept for 2× 2-block operator matrices–the quadratic numerical range–
is studied. The main results are a spectral inclusion theorem, an estimate of the resolvent in …

Here is some advice to make this book easier to read. In order to check/deepen the
understanding of the material and to facilitate independent work the reader is supplied with …

The theory of linear damped oscillations was originally developed more than hundred years
ago and is still of vital research interest to engineers, mathematicians and physicists alike …

In this paper we establish a new analytic enclosure for the spectrum of unbounded linear
operators A admitting a block operator matrix representation. For diagonally dominant and …

In this paper, we establish an analytic enclosure for the spectrum of unbounded linear
operators~ A admitting an n*n matrix representation in a Hilbert space H=H_1⊕⋯⊕H_n. For …

We introduce the new notion of the block numerical range for bounded n× n block operator
matrices. The main results concern spectral inclusion, inclusion between block numerical …

We introduce concepts of essential numerical range for the linear operator pencil. In contrast
to the operator essential numerical range, the pencil essential numerical ranges are, in …

Existence and Uniqueness of Contractive Solutions of Some Riccati Equations Page 1
Journal of Functional Analysis 179, 448 473 (2001) Existence and Uniqueness of …

On the Boundedness of Hamiltonian Operators Page 1 PROCEEDINGS OF THE AMERICAN
MATHEMATICAL SOCIETY Volume 131, Number 2, Pages 563-576 S 0002-9939(02)06565-6 …