Preface §P.1.How this book came to be, and its peculiarities §P.2.A bird's eye view of hyperbolic equations Chapter 1.Simple Examples of Propagation §1.1.The method of characteristics §1.2.Examples of propagation of singularities using progressing waves §1.3.Group velocity and the method of nonstationary phase §1.4.Fourier synthesis and rectilinear propagation §1.5.A cautionary example in geometric optics §1.6.The law of reflection 1.6.1.The method of images 1.6.2.The plane wave derivation 1.6.3.Reflected high frequency wave packets §1.7.Snell's law of refraction Chapter 2.The Linear Cauchy Problem §2.1.Energy estimates for symmetric hyperbolic systems §2.2.Existence theorems for symmetric hyperbolic systems 62.3.Finite speed of propagation 2.3.1.The method of characteristics 2.3.2.Speed estimates uniform in space 2.3.3.Time-like and propagation cones §2.4.Plane waves, group velocity, and phase velocities §2.5.Precise speed estimate §2.6.Local Cauchy problems Appendix 2.I.Constant coefficient hyperbolic systems Appendix 2.II.Functional analytic proof of existence Chapter 3.Dispersive Behavior §3.1.Orientation §3.2.Spectral decomposition of solutions §3.3.Large time asymptotics §3.4.Maximally dispersive systems 3.4.1.The L1 → Lo decay estimate 3.4.2.Fixed time dispersive Sobolev estimates 3.4.3.Strichartz estimates Appendix 3.I.Perturbation theory for semisimple eigenvalues Appendix 3.IⅡ.The stationary phase inequality Chapter 4.Linear Elliptic Geometric Optics §4.1.Euler's method and elliptic geometric optics with constant coefficients §4.2.Iterative improvement for variable coefficients and nonlinear phases §4.3.Formal asymptotics approach §4.4.Perturbation approach §4.5.Elliptic regularity §4.6.The Microlocal Elliptic Regularity Theorem Chapter 5.Linear Hyperbolic Geometric Optics §5.1.Introduction §5.2.Second order scalar constant coefficient principal part 5.2.1.Hyperbolic problems 5.2.2.The quasiclassical limit of quantum mechanics §5.3.Symmetric hyperbolic systems §5.4.Rays and transport 5.4.1.The smooth variety hypothesis 5.4.2.Transport for L = L1(θ) 5.4.3.Energy transport with variable coefficients §5.5.The Lax para metrix and propagation of singularities 5.5.1.The Lax parametrix 5.5.2.Oscillatory integrals and Fourier integral operators 5.5.3.Small time propagation of singularities 5.5.4.Global propagation of singularities §5.6.An application to stabilization Appendix 5.I.Hamilton-Jacobi theory for the eikonal equation 5.I.1.Introduction 5.I.2.Determining the germ of o at the initial manifold 5.I.3.Propagation laws for φ, dφ 5.I.4.The symplectic approach Chapter 6.The Nonlinear Cauchy Problem §6.1.Introduction §6.2.Schauder's lemma and Sobolev embedding §6.3.Basic existence theorem §6.4.Moser's inequality and the nature of the breakdown §6.5.Perturbation theory and smooth dependence §6.6.The Cauchy problem for quasilinear symmetric hyperbolic systems 6.6.1.Existence of solutions 6.6.2.Examples of breakdown 6.6.3.Dependence on initial data §6.7.Global small solutions for maximally dispersive nonlinear systems §6.8.The subcritical nonlinear Klein-Gordon equation in the energy space 6.8.1.Introductory remarks 6.8.2.The ordinary differential equation and non-lipshitzean F 6.8.3.Subcritical nonlinearities Chapter 7.One Phase Nonlinear Geometric Optics §7.1.Amplitudes and harmonics §7.2.Elementary examples of generation of harmonics §7.3.Formulating the ansatz §7.4.Equations for the profiles §7.5.Solving the profile equations Chapter 8.Stability for One Phase Nonlinear Geometric Optics §8.1.The H8(Rd) norms §8.2.Hs estimates for linear symmetric hyperbolic systems §8.3.Just