Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fourth-post-Newtonian-exact approximation to General Relativity   An approximation to General Relativity is presented that agrees with the
Einstein field equations up to and including the fourth post-Newtonian (PN)
order. This approximation is formulated in a fully constrained scheme: all
involved equations are explicitly elliptic except the wave equation that
describes the two independent degrees of freedom of the gravitational field.
The formalism covers naturally the conformal-flat-condition (CFC) approach by
Isenberg, Wilson, and Mathews and the improved second PN-order exact approach
CFC+. For stationary configurations, like Kerr black holes, agreement with
General Relativity is achieved even through 5PN order. In addition, a
particularly interesting 2PN-exact waveless approximation is analyzed in
detail, which results from imposing more restrictive conditions. The proposed
scheme can be considered as a further development on the waveless approach
suggested by Schaefer and Gopakumar [Phys. Rev. D {\bf 69}, 021501 (2004)].

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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
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The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
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The categories of this paper are: eess