Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Reversibility of time series: revealing the hidden messages in X-ray
  binaries and cataclysmic variables
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math