Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Structural identifiability analysis of PDEs: A case study in continuous
  age-structured epidemic models
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th