Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Unproceedings of the Fourth .Astronomy Conference (.Astronomy 4),
  Heidelberg, Germany, July 9-11 2012
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom