35A23 Inequalities applied to PDEs involving derivatives, differential and integral operators, or integrals 1232

35A27 Microlocal methods and methods of sheaf theory and homological algebra applied to PDEs [See also 32C38, 58J15] 1158

35A30 Geometric theory, characteristics, transformations in context of PDEs [See also 58J70, 58J72] 5120