Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Approximate nonlinear self-adjointness and approximate conservation laws   In this paper, approximate nonlinear self-adjointness for perturbed PDEs is
introduced and its properties are studied. Consequently, approximate
conservation laws which cannot be obtained by the approximate Noether theorem
are constructed by means of the method. As an application, a class of perturbed
nonlinear wave equations is considered to illustrate the effectiveness.

16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th