35A01 Existence problems: global existence, local existence, non-existence

35A02 Uniqueness problems: global uniqueness, local uniqueness, non-uniqueness

35A16 Topological and monotonicity methods

35A22 Transform methods (e.g. integral transforms)

35A23 Inequalities  involving derivatives and differential and integral operators, inequalities for integrals

35A24 Methods of ordinary differential equations

35A27 Microlocal methods; methods of sheaf theory and homological algebra in PDE [See also <a href="#code:32C38">32C38</a>, <a href="#code:58J15">58J15</a>]

35A30 Geometric theory, characteristics, transformations [See also <a href="#code:58J70">58J70</a>, <a href="#code:58J72">58J72</a>]

35A35 Theoretical approximation to solutions {For numerical analysis, see <a href="#code:65Mxx">65Mxx</a>, <a href="#code:65Nxx">65Nxx</a>}

35A99 None of the above, but in this section

35Bxx Qualitative properties of solutions

35B05 Oscillation, zeros of solutions, mean value theorems, etc.

35B15 Almost and pseudo-almost periodic solutions

35B27 Homogenization;  equations in media with periodic structure [See also <a href="#code:74Qxx">74Qxx</a>, <a href="#code:76M50">76M50</a>]

35B30 Dependence of solutions on initial and boundary data, parameters [See also <a href="#code:37Cxx">37Cxx</a>]

35B32 Bifurcation [See also <a href="#code:37Gxx">37Gxx</a>, <a href="#code:37K50">37K50</a>]

35B53 Liouville theorems, Phragmén-Lindelöf theorems

35B60 Continuation and prolongation of solutions  [See also <a href="#code:58A15">58A15</a>, <a href="#code:58A17">58A17</a>, <a href="#code:58Hxx">58Hxx</a>]

35B65 Smoothness and regularity of solutions

35B99 None of the above, but in this section

35C15 Integral representations of solutions

35C99 None of the above, but in this section

35D99 None of the above, but in this section

35Exx Equations and systems with constant coefficients [See also <a href="#code:35N05">35N05</a>]

35E99 None of the above, but in this section

35Fxx General first-order equations and systems

35F10 Initial value problems for linear first-order equations