Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Gowdy-symmetric vacuum and electrovacuum solutions   We construct a 4-parameter family of inhomogeneous cosmological models, which
contains two recently derived 3-parameter families as special cases. The
corresponding exact vacuum solution to Einstein's field equations is obtained
with methods from soliton theory. We also study properties of these models and
find that they combine all interesting features of both earlier solution
families: general regularity within the maximal globally hyperbolic region,
particular singular cases in which a curvature singularity with a directional
behaviour forms, a highly non-trivial causal structure, and Cauchy horizons
whose null generators can have both closed or non-closed orbits. In the second
part of the paper, we discuss the generalization from vacuum to electrovacuum.
Moreover, we also present a family of exact solutions for that case and study
its properties.

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The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
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The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: bayes-an
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The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ex
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph