Differential equations, Partial Hamiltonian operator Hamiltonian systems Kolmogorov-Arnold-Moser theory Nonlinear oscillations Wave equation Capillarity Cauchy problem Dynamical systems and ergodic theory [See also 26A18, 28Dxx, 34Cxx, 34Dxx, 35Bxx, 46Lxx, 58Jxx, 70-XX] -- Infinite-dimensional Hamiltonian systems [See also 35Axx, 35Qxx] -- Bifurcation problems Dynamical systems and ergodic theory [See also 26A18, 28Dxx, 34Cxx, 34Dxx, 35Bxx, 46Lxx, 58Jxx, 70-XX] -- Infinite-dimensional Hamiltonian systems [See also 35Axx, 35Qxx] -- Perturbations, KAM for inf Fluid mechanics {For general continuum mechanics, see 74Axx, or other parts of 74-XX} -- Incompressible inviscid fluids -- Water waves, gravity waves; dispersion and scattering, nonlinear interaction Fluid mechanics {For general continuum mechanics, see 74Axx, or other parts of 74-XX} -- Incompressible viscous fluids -- Capillarity (surface tension) [See also 76B45] Implicit functions Mathematical models Numerical solutions Partial differential equations -- Pseudodifferential operators and other generalizations of partial differential operators [See also 47G30, 58J40] -- Pseudodifferential operators Perturbation (Mathematics) Schrödinger equation Sobolev spaces Standing waves Water waves