Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Limit from the X-ray Background on the Contribution of Quasars to
  Reionization
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int