Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Polarization singularities and M\"{o}bius strips in sound and
  water-surface waves
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex