Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: First-principles study on luminescence properties of Eu-doped defect
  pyrochlore oxide KNbWO$_6\cdot$H$_2$O:Eu$^{3+}$
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph