A counterexample to an isomorphism problem for power monoids
Commutative Algebra
2025-09-30 v1 Combinatorics
Abstract
Let be a (multiplicatively written) monoid. The family of finite subsets of containing the identity element is itself a monoid when endowed with setwise multiplication induced by . Tringali and Yan proved that two monoids and contained in a special class of commutative, cancellative monoids are isomorphic if and only if and are. Moreover, they raised the question whether the same holds in the general setting of cancellative monoids. We show that if and are (commutative) valuation monoids with trivial unit groups and isomorphic quotient groups, then . This provides a negative answer to Tringali and Yans question already within the class of valuation submonoids of the additive group .
Keywords
Cite
@article{arxiv.2509.23818,
title = {A counterexample to an isomorphism problem for power monoids},
author = {Balint Rago},
journal= {arXiv preprint arXiv:2509.23818},
year = {2025}
}