Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Higher order gravities and the Strong Equivalence Principle   We show that, in all metric theories of gravity with a general covariant
action, gravity couples to the gravitational energy-momentum tensor in the same
way it couples to the matter energy-momentum tensor order by order in the weak
field approximation around flat spacetime. We discuss the relation of this
property to the Strong Equivalence Principle. We also study the gauge
transformation properties of the gravitational energy-momentum tensor.

9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs