Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Foliation dependence of black hole apparent horizons in spherical
  symmetry   Numerical studies of gravitational collapse to black holes make use of
apparent horizons, which are intrinsically foliation-dependent. We expose the
problem and discuss possible solutions using the Hawking quasilocal mass. In
spherical symmetry, we present a physically sensible approach to the problem by
restricting to spherically symmetric spacetime slicings. In spherical symmetry
the apparent horizons are gauge-independent in any spherically symmetric
foliation but physical quantities associated with them, such as surface gravity
and temperature, are not. The widely used comoving and Kodama foliations, which
are of particular interest, are discussed in detail.

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The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
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The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
3
The categories of this paper are: physics
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg