Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Operations preserving equivalence relations   In 2014, C\'egielski, Grigorieff and Guessarian characterized unary self-maps
on the set $\mathbb{Z}$ of integers which preserve all congruences of the
additive group. In this note, we propose a shorter and straigthforward proof.
We replace this result in the frame of universal algebra.

7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat