Differential equations, Partial Équations aux dérivées partielles Analyse harmonique Harmonic analysis Asymptotic distribution of eigenvalues and eigenfunctions Boundary value problems Difference and functional equations Differential equations, Nonlinear Elasticity Espaces de Sobolev Espaces homogènes Essays Existence, uniqueness, and regularity theory [See also 35Q30] Élasticité Équations différentielles non linéaires Fluid mechanics {For general continuum mechanics, see 74Axx, or other parts of 74-XX} Fourier Analysis Function spaces arising in harmonic analysis Functional analysis {For manifolds modeled on topological linear spaces, see 57Nxx, 58Bxx} Functional equations and inequalities [See also 30D05] General General higher-order equations and systems Geometric optics Harmonic analysis in several variables {For automorphic theory, see mainly 11F30} Harmonic analysis on Euclidean spaces Homogeneous spaces Incompressible viscous fluids Integral representations, integral operators, integral equations methods Linear function spaces and their duals [See also 30H05, 32A38, 46F05] {For function algebras, see 46J10} MATHEMATICS