English

Torsion factors of commutative monoid semirings

Rings and Algebras 2024-01-23 v1

Abstract

Let PP be a finitely generated commutative semiring. It was shown recently that if PP is a parasemifield (i.e. the multiplicative reduct of PP is a group) then PP cannot contain the positive rationals Q+\mathbb{Q}^+ as its subsemiring. Equivalently, a commutative parasemifield PP finitely generated as a semiring is additively divisible if and only if PP is additively idempotent. We generalize this result using weaker forms of these additive properties to a broader class of commutative semirings in the following way. Let SS be a semiring that is a factor of a monoid semiring N[C]\mathbb{N}[\mathcal{C}] where C\mathcal{C} is a submonoid of a free commutative monoid of finite rank. Then the semiring SS is additively almost-divisible if and only if SS is torsion. In particular, we show that if SS is a ring then SS cannot contain any non-finitely generated subring of Q\mathbb{Q}.

Keywords

Cite

@article{arxiv.2401.11602,
  title  = {Torsion factors of commutative monoid semirings},
  author = {Miroslav Korbelář},
  journal= {arXiv preprint arXiv:2401.11602},
  year   = {2024}
}