Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The age, life expectancy, and space density of Post Common Envelope
  Binaries
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th