Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: On Liouville type theorems for the stationary MHD and the Hall-MHD
  systems in $\mathbb{R}^3$
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics