Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Optical Depth of the Cosmic Microwave Background and Reionization of the
  Intergalactic Medium
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph