Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Topologically nontrivial solution in Einstein-Dirac gravity on the Hopf
  bundle
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat