Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The structure of infinite 2-groups with a unique 2-element subgroup   We prove that each infinite 2-group with a unique 2-element subgroup is
isomorphic either to the quasicyclic 2-group or to the infinite group of
generalized quaternions.

32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th