On rings as unions of four subrings
Rings and Algebras
2020-09-09 v2 Commutative Algebra
Abstract
The covering number of an associative ring is the minimal number of proper subrings whose union is . We establish a strategy to classify unital rings of a given finite covering number, and obtain a classification of unital rings whose covering number is four. Along the way we compute the covering number of every finite local ring whose residue field has prime order.
Cite
@article{arxiv.2008.03803,
title = {On rings as unions of four subrings},
author = {Jon Cohen},
journal= {arXiv preprint arXiv:2008.03803},
year = {2020}
}
Comments
Article reorganized; full classification now proved