Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The structure of two-valued strategy-proof social choice functions with
  indifference
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol