Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Photoemission study of polycrystalline Gd_{1-x}Sr_xTiO_{3+delta}:
  correlation and surface effects
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc