Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calabi-Yau threefolds of quotient type   First, we classify Calabi-Yau threefolds with infinite fundamental group by
means of their minimal splitting coverings introduced by Beauville, and deduce
that the nef cone is a rational simplicial cone and any rational nef divisor is
semi-ample if the second Chern class is identically zero. We also derive a
sufficient condition for the fundamental group to be finite in terms of the
Picard number in an optimal form. Next, we give a concrete structure Theorem
concerning $c_{2}$-contractions of Calabi-Yau threefolds as a generalisation
and also a correction of our earlier works for simply connected ones. Finally,
as an application, we show the finiteness of the isomorphism classes of
$c_{2}$-contractions of each Calabi-Yau threefold.

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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph