Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Simple Analytic Models of Gravitational Collapse   Most general relativity textbooks devote considerable space to the simplest
example of a black hole containing a singularity, the Schwarzschild geometry.
However only a few discuss the dynamical process of gravitational collapse, by
which black holes and singularities form. We present here two types of analytic
models for this process, which we believe are the simplest available; the first
involves collapsing spherical shells of light, analyzed mainly in
Eddington-Finkelstein coordinates; the second involves collapsing spheres
filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand
coordinates. Our main goal is pedagogical simplicity and algebraic
completeness, but we also present some results that we believe are new, such as
the collapse of a light shell in Kruskal-Szekeres coordinates.

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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
0
The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol