Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A finite presentation for the twist subgroup of the mapping class group
  of a nonorientable surface
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an