Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Boundary Ground Ring in Minimal String Theory   We obtain relations among boundary states in bosonic minimal open string
theory using the boundary ground ring. We also obtain a difference equation
that boundary correlators must satisfy.

2
The categories of this paper are: math
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys