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 …

We consider local energy decay estimates for solutions to scalar wave equations on
nontrapping asymptotically flat space-times. Our goals are two-fold. First we consider the …

We study the inverse spectral problem of reconstructing energy-dependent Sturm–Liouville
equations from their Dirichlet spectra and sequences of the norming constants. For the class …

We give a relativistic generalization of the Gutzwiller-Duistermaat-Guillemin trace formula for
the wave group of a compact Riemannian manifold to globally hyperbolic stationary space …

In this paper we study the inverse spectral problem of reconstructing energy-dependent
Sturm–Liouville equations from two spectra. We give a reconstruction algorithm and …

In this paper the spectral properties of the abstract Klein–Gordon equation are studied. The
main tool is an indefinite inner product known as the charge inner product. Under certain …

We propose a method for the spectral analysis of unbounded operator matrices in a general
setting which fully abstains from standard perturbative arguments. Rather than requiring the …

In this paper, we study the inverse scattering problem for ZS-AKNS systems on the half-line
with general boundary conditions at the origin. For the class of potentials with certain …

We analyze new phenomena arising in linear damped wave equations on unbounded
domains when the damping is allowed to become unbounded at infinity. We prove the …

We establish a new method for obtaining nonconvex spectral enclosures for operators
associated with second‐order differential equations in a Hilbert space. In particular, we …