Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hopf hypersurfaces in complex Grassmannians of rank two   In this paper, we study real hypersurfaces in complex Grassmannians of rank
two. First, the nonexistence of mixed foliate real hypersurfaces is proven.
With this result, we show that for Hopf hypersurfaces in complex Grassmannians
of rank two, the Reeb principal curvature is constant along integral curves of
the Reeb vector field. As a result the classification of contact real
hypersurfaces is obtained. We also introduce the notion of $q$-umbilical real
hypersurfaces in complex Grassmannians of rank two and obtain a classification
of such real hypersurfaces.

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The categories of this paper are: adap-org
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The categories of this paper are: eess
28
The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
3
The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th