Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Existence theory and qualitative analysis for a fully cross-diffusive
  predator-prey system
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int