Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The quantum spin Hall effect and topological insulators   In topological insulators, spin-orbit coupling and time-reversal symmetry
combine to form a novel state of matter predicted to have exotic physical
properties.

3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom