Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Principal configurations around umbilics of spacelike surfaces in null
  hypersurfaces of $\mathbb{R}_1^4$   We study the principal configurations around an isolated $\eta$-umbilical
point on a generic spacelike surface $S$ immersed in a null hypersurface $M$ of
Minkowski space $\mathbb{R}_1^4$ relative to a well-defined null vector field
$\eta$ orthogonal to the surface $S$. In the particular case of $M$ being a
null rotation hypersurface of $\mathbb{R}_1^4$ we also recover the local
Darbouxian principal configurations around that kind of $\eta$-umbilical
points.

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The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
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The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
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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: ao-sci
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The categories of this paper are: gr-qc
3
The categories of this paper are: physics