The aim of this book is to give a rigorous and complete treatment of various topics from
harmonic analysis with a strong emphasis on symplectic invariance properties, which are …

This authoritative text studies pseudodifferential and Fourier integral operators in the
framework of time-frequency analysis, providing an elementary approach, along with …

A class of inverse problems for restoring the right-hand side of a parabolic equation for a
large class of positive operators with discrete spectrum is considered. The results on …

The monograph gives a detailed exposition of the theory of general elliptic operators (scalar
and matrix) and elliptic boundary value problems in Hilbert scales of Hörmander function …

We study the null-controllability of parabolic equations associated with a general class of
hypoelliptic quadratic differential operators. Quadratic differential operators are operators …

In this paper we study weakly hyperbolic second order equations with time dependent
irregular coefficients. This means assuming that the coefficients are less regular than Hölder …

Given a Hilbert space HH, we investigate the well-posedness of the Cauchy problem for the
wave equation for operators with a discrete non-negative spectrum acting on H H. We …

The paper gives a detailed survey of recent results on elliptic problems in Hilbert spaces of
generalized smoothness. The latter are the isotropic Hörmander spaces $ H^{s,\varphi}:= B …

This paper deals with the multi-term generalisation of the time-fractional diffusion-wave
equation for general operators with discrete spectrum, as well as for positive hypoelliptic …

We consider the semi-classical (or Gutzwiller–Voros) zeta functions for C^ ∞ C∞ contact
Anosov flows. Analyzing the spectra of the generators of some transfer operators associated …