Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The HETDEX Pilot Survey. IV. The Evolution of [O II] Emitting Galaxies
  from z ~ 0.5 to z ~ 0
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn