Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Spectral gaps of the one-dimensional Schr\"odinger operators with
  singular periodic potentials
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys