Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The moduli space of left-invariant metrics of a class of six-dimensional
  nilpotent Lie groups
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph