Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A hole in the sky - The dependence of the galaxy luminosity function on
  the environment   We have developed a method to calculate overdensities in multicolour surveys,
and compare the local density contrast measured in galaxy samples with
different redshift error distributions. We calculated overdensities for three
COMBO-17 fields, and identified a region in the CDFS, where the density is
lower by a factor of 2 compared to the other two fields. This is mainly due to
a deficiency of faint red galaxies. This result is in agreement with local
observations in the 2dF.

36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess