Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the water-bag model of dispersionless KP hierarchy (II)   We construct the bi-Hamiltonian structure of the waterbag model of dKP and
establish the third-order Hamiltonian operator associated with the waterbag
model. Also, the symmetries and conserved densities of rational type are
discussed.

37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph