Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: To the practical design of the optical lever intracavity topology of
  gravitational-wave detectors
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph