Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A norm knockout method on indirect reciprocity to reveal indispensable
  norms
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th