Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The Deep Chandra Survey of the Groth Strip - II. optical identification
  of the X-ray sources
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex