Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The road to gravitational-wave astronomy   Gravitational-wave astronomy is an area of great promise, yet to be realized.
While we are waiting for the first (undisputed!) direct detection of these
elusive waves it is useful to take stock and consider the challenges that need
to be met if we want this field to reach its full potential. This write-up
provides a brief introduction to some of the key ideas and the current
state-of-play, and lists a range of modelling questions that need to be
considered in the future.

25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con