Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Take the A-Metric: Interpretations of Some Known Solutions of Einstein's
  Vacuum Field Equations   In this work, we present a new interpretation of the only static vacuum
solution of Einstein's field equations with planar symmetry, the Taub solution.
This solution is a member of the $AIII$ class of metrics, along with the type D
Kasner solution. Various interpretations of these solutions have been put
forward previously in the literature, however, some of these interpretations
have suspect features and are not generally considered physical. Using a simple
mathematical analysis, we show that a novel interpretation of the Taub solution
is possible and that it naturally emerges from the radial, near-singularity
limit of negative-mass Schwarzschild spacetime. A new, more transparent
derivation is also given showing that the type D Kasner metric can be
interpreted as a region of spacetime deep within a positive-mass Schwarzschild
black hole. The dual nature of this class of $A$-metrics is thereby
demonstrated.

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The categories of this paper are: physics
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin