Geometric proofs of composition theorems for generalized Fourier integral operators.
Geometry of stationary sets for the wave equation in . The case of finitely supported initial data: An announcement.
Global time estimates for solutions to equations of dissipative type
Global time estimates of norms of solutions to general strictly hyperbolic partial differential equations are considered. The case of special interest in this paper are equations exhibiting the dissipative behaviour. Results are applied to discuss time decay estimates for Fokker-Planck equations and for wave type equations with negative mass.