Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Which quantum theory must be reconciled with gravity? (And what does it
  mean for black holes?)
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg