Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Superconducting gap symmetry in BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$
  superconductor
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga