Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: MMT observations of new extremely metal-poor emission-line galaxies in
  the Sloan Digital Sky Survey
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph