Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Gibbons--Tsarev equation: symmetries, invariant solutions, and
  applications   In this paper we present the full classification of the symmetry-invariant
solutions for the Gibbons--Tsarev equation. Then we use these solutions to
construct explicit expressions for reductions of Benney's moments equations, to
get solutions of Pavlov's equation, and to find integrable reductions of the
Ferapontov--Huard--Zhang system, which describes implicit two-phase solutions
of the dKP equation.

25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph