Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On closure operators and reflections in Goursat categories   By defining a closure operator on effective equivalence relations in a
regular category $C$, it is possible to establish a bijective correspondence
between these closure operators and the regular epireflective subcategories $L$
of $C$. When $C$ is an exact Goursat category this correspondence restricts to
a bijection between the Birkhoff closure operators on effective equivalence
relations and the Birkhoff subcategories of $C$. In this case it is possible to
provide an explicit description of the closure, and to characterise the
congruence distributive Goursat categories.

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The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg