English

Semigroups of ideals and isomorphism problems

Rings and Algebras 2025-04-04 v1 Combinatorics

Abstract

Let HH be a monoid (written multiplicatively). We call HH Archimedean if, for all a,bHa, b \in H such that bb is a non-unit, there is an integer k1k \ge 1 with bkHaHb^k \in HaH; strongly Archimedean if, for each aHa \in H, there is an integer k1k \ge 1 such that HaHHaH contains any product of any kk non-units of HH; and duo if aH=HaaH = Ha for all aHa \in H. We prove that the ideals of two strongly Archimedean, cancellative, duo monoids make up isomorphic semigroups under the induced operation of setwise multiplication if and only if the monoids themselves are isomorphic up to units; and the same holds upon restriction to finitely generated ideals in Archimedean, cancellative, duo monoids. Then we use the previous results to tackle a new case of a problem of Tamura and Shafer from the late 1960s.

Keywords

Cite

@article{arxiv.2410.15622,
  title  = {Semigroups of ideals and isomorphism problems},
  author = {Pedro A. Garcia-Sanchez and Salvatore Tringali},
  journal= {arXiv preprint arXiv:2410.15622},
  year   = {2025}
}

Comments

12 pp., to appear in Proceedings of the Amer. Math. Soc

R2 v1 2026-06-28T19:29:05.640Z