Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The gravimagnetic dipole   We investigate a previously constructed stationary solution of the vacuum
Einstein equations, which represents a system of two non-extreme black holes
with equal masses and opposite NUT charges, connected by a Misner string with
tension. For large separations, the inverse square law force measured by this
tension is attractive or repulsive, according to the relative values of the
masses and NUT charges. For small separations, the force is always repulsive,
so that the system cannot collapse to a single black hole. For given values of
the black hole masses and NUT charges, there is a unique configuration such
that the Misner string is tensionless. This behaves asymptotically as the Kerr
solution, but can be overspinning while remaining free from a ring singularity,
thus evading the usual black hole uniqueness theorems. All double black hole
and string configurations satisfy a generalized first law of black hole
mechanics where the two black holes and the Misner string are treated on an
equal footing.

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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: quant-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
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn