English

On Ehresmann semigroups

Category Theory 2021-04-21 v2

Abstract

We formulate an alternative approach to describing Ehresmann semigroups by means of left and right \'etale actions of a meet semilattice on a category. We also characterize the Ehresmann semigroups that arise as the set of all subsets of a finite category. As applications, we prove that every restriction semigroup can be nicely embedded into a restriction semigroup constructed from a category, and we describe when a restriction semigroup can be nicely embedded into an inverse semigroup.

Keywords

Cite

@article{arxiv.2102.12250,
  title  = {On Ehresmann semigroups},
  author = {Mark V Lawson},
  journal= {arXiv preprint arXiv:2102.12250},
  year   = {2021}
}
R2 v1 2026-06-23T23:28:18.259Z