Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: On the existence of the Green function for elliptic systems in
  divergence form
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio