Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasi-Local Energy Conservation Law Derived From The Einstein's
  Equations   The quasi-local energy conservation law is derived from the vacuum Einstein's
equations on the timelike boundary surface in the canonical (2,2)-formalism of
general relativity. The quasi-local energy and energy flux integral agree with
the standard results in the asymptotically flat limit and in spherically
symmetric spacetimes.

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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: funct-an