Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Dark energy perturbations and a possible solution to the coincidence
  problem
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph