Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The non-commutative Korteweg--de Vries hierarchy and combinatorial Poppe
  algebra
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex