Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quadratic equations over free groups are NP-complete   We prove that the problems of deciding whether a quadratic equation over a
free group has a solution is NP-complete.

36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg