Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Non-Existence of Black Hole Solutions to Static, Spherically Symmetric
  Einstein-Dirac Systems - a Critical Discussion
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys