Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Co-Hopfian virtually free groups and elementary equivalence   We prove that two co-Hopfian finitely generated virtually free groups are
elementarily equivalent if and only if they are isomorphic. We also prove that
co-Hopfian finitely generated virtually free groups are homogeneous in the
sense of model theory.

33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
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
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics