Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A presentation for the mapping class group of a nonorientable surface   Let $N_{g,n}$ denote the nonorientable surface of genus $g$ with $n$ boundary
components and $M(N_{g,n})$ its mapping class group. We obtain an explicit
finite presentation of $M(N_{g,n})$ for $n=0,1$ and all $g$ such that $g+n>3$.

15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
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The categories of this paper are: nlin
10
The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph