Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A note on covers defining relative and sectional categories   We give a characterization of relative category in the sense of Doeraene-El
Haouari by using open covers. We also prove that relative category and
sectional category can be defined by taking arbitrary covers (not necessarily
open) when dealing with ANR spaces.

27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
3
The categories of this paper are: physics
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol