Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Klein bottle group is not strongly verbally closed, though awfully
  close to being so   According to Mazhuga's theorem, the fundamental group $H$ of any connected
surface, possibly except for the Klein bottle, is a retract of each finitely
generated group containing $H$ as a verbally closed subgroup. We prove that the
Klein bottle group is indeed an exception but has a very close property.

7
The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
1
The categories of this paper are: cs
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The categories of this paper are: stat
12
The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat