Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational field of gyratons on various background spacetimes   In this work we have found and analyzed several gyraton solutions on various
non--trivial backgrounds in the large Kundt class of spacetimes. Namely, the
gyraton solutions on direct product spacetimes, gyraton solutions on Melvin
universe and its generalization which includes the cosmological constant. These
solutions are of algebraic type II. Also we have investigated type III
solutions within the Kundt class and we have found the gyratons on de Sitter
spacetime. We have generalized the gyraton solutions on direct product
spacetimes to higher dimensions. The chapters 4 and 5 are published for the
first time.

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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: econ
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph