Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Strong solutions and weak-strong stability in a system of
  cross-diffusion equations
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con