Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Filtered expansions in general relativity I   This is the first of two papers in which we construct formal power series
solutions in external parameters to the vacuum Einstein equations, implementing
one bounce for the Belinskii-Khalatnikov-Lifshitz (BKL) proposal for spatially
inhomogeneous spacetimes. We use a graded Lie algebra, homological framework. A
dedicated filtration encodes key features of the BKL proposal, and we use it to
set up an unobstructed perturbative problem.

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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol