English

On internal categories and crossed objects in the category of monoids

Category Theory 2024-01-04 v1

Abstract

It is a well-known fact that the category Cat(C)\mathsf{Cat}(\mathbf{C}) of internal categories in a category C\mathbf{C} has a description in terms of crossed modules, when C=Gr\mathbf{C}=\mathbf{Gr} is the category of groups. The proof of this result heavily uses the fact that any split epimorphism decomposes as a semi-direct product. An equivalent statement does not hold in the category Mon\mathbf{Mon} of monoids. In a previous work on quadratic algebras, I constructed an internal category in the category of monoids, see Section 6. Based on this construction, this paper will introduce the notion of a crossed semi-bimodule and show that it gives rise to an object in Cat(Mon)\mathsf{Cat}(\mathbf{Mon}). I will also relate this new notion to the crossed semi-modules introduced earlier by A. Patchkoria.

Keywords

Cite

@article{arxiv.2401.01863,
  title  = {On internal categories and crossed objects in the category of monoids},
  author = {Ilia Pirashvili},
  journal= {arXiv preprint arXiv:2401.01863},
  year   = {2024}
}