Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Interaction of inhomogeneous axions with magnetic fields in the early
  universe
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics