Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Canonical Analysis of Radiating Atmospheres of Stars in Equilibrium   The spherically symmetric, static spacetime generated by a cross-flow of
non-interacting null dust streams can be conveniently interpreted as the
radiation atmosphere of a star, which also receives exterior radiation.
Formally, such a superposition of sources is equivalent to an anisotropic
fluid. Therefore, there is a preferred time function in the system, defined by
this reference fluid. This internal time is employed as a canonical coordinate,
in order to linearize the Hamiltonian constraint. This turns to be helpful in
the canonical quantization of the geometry of the radiating atmosphere.

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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: eess
26
The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph