Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: On the number of Nambu-Goldstone bosons and its relation to charge
  densities
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas