Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Structures in galaxies: nature versus nurture. Input from theory and
  simulations
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th