Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The stability of modified gravity models   Conditions for the existence and stability of de Sitter space in modified
gravity are derived by considering inhomogeneous perturbations in a
gauge-invariant formalism. The stability condition coincides with the
corresponding condition for stability with respect to homogeneous
perturbations, while this is not the case in scalar-tensor gravity. The
stability criterion is applied to various modified gravity models of the early
and the present universe.

30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph