Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The spin-1/2 square-lattice J_1-J_2 model: The spin-gap issue
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc