Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the various aspects of electromagnetic potentials in spacetimes with
  symmetries   We revise and generalize the properties of the electric and the magnetic
scalar potentials in spacetimes admitting a Killing vector field: Their
constancy on the Killing horizons, uniqueness of solution for the
electromagnetic test fields and the relation between the Bianchi identity and
Maxwell's equations. In each of these examples, collinearity of currents with
the Killing vector field is shown to be the crucial property.

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The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
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The categories of this paper are: alg-geom
2
The categories of this paper are: math
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas