Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Instability of natural convection in a laterally heated cube with
  perfectly conducting horizontal boundaries
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org