Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Pre-proceedings of the 31st International Symposium on Logic-Based
  Program Synthesis and Transformation (LOPSTR 2021)
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th