Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Probing the universe with the Lyman-alpha forest: III. The mean opacity
  of the IGM   The paper is withdrawn.

28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph