Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal central extensions of internal crossed modules via the
  non-abelian tensor product   In the context of internal crossed modules over a fixed base object in a
given semi-abelian category, we use the non-abelian tensor product in order to
prove that an object is perfect (in an appropriate sense) if and only if it
admits a universal central extension. This extends results of Brown-Loday (in
the case of groups) and Edalatzadeh (in the case of Lie algebras). Our aim is
to explain how those results can be understood in terms of categorical Galois
theory: Edalatzadeh's interpretation in terms of quasi-pointed categories
applies, but a more straightforward approach based on the theory developed in a
pointed setting by Casas and the second author works as well.

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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
14
The categories of this paper are: math-ph
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The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
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The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci