Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A lower bound of the Trautman-Bondi energy   We obtain an energy inequality on null surfaces $u=const$ in the Bondi-Sachs
formalism. We show that for a sufficiently regular event horizon $H$ there is
an affine radial coordinate which is constant on $H$. Then the energy
inequality can be prolongated to the horizon giving an estimation which is
closely related to the Penrose inequality. We test it for the Kerr solution
written in the Fletcher-Lun coordinates.

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The categories of this paper are: math
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
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The categories of this paper are: astro-ph
16
The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat