Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Two-fluid stellar objects in General Relativity: the covariant
  formulation
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg