Subintegrality and ideal class groups of monoid algebras

Fuente: arXiv
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Main Authors: Raihan, Md Abu, Roberts, Leslie G., Sarwar, Husney Parvez
Format: Preprint
Published: 2025
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author Raihan, Md Abu
Roberts, Leslie G.
Sarwar, Husney Parvez
author_facet Raihan, Md Abu
Roberts, Leslie G.
Sarwar, Husney Parvez
contents $(1)$ Let $M\subset N$ be a commutative cancellative torsion-free and subintegral extension of monoids. Then we prove that in the case of ring extension $A[M]\subset A[N]$, the two notions, subintegral and weakly subintegral coincide provided $\mathbb{Z}\subset A$. $(2)$ Let $A \subset B$ be an extension of commutative rings and $M\subset N$ an extension of commutative cancellative torsion-free positive monoids. Let $I$ be a radical ideal in $N$. Then $\frac{A[M]}{(I\cap M)A[M]}$ is subintegrally closed in $\frac{B[N]}{IB[N]}$ if and only if the group of invertible $A$-submodules of $B$ is isomorphic to the group of invertible $\frac{A[M]}{(I\cap M)A[M]}$-submodules of $\frac{B[N]}{IB[N]}$.
format Preprint
id arxiv_https___arxiv_org_abs_2507_13845
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Subintegrality and ideal class groups of monoid algebras
Raihan, Md Abu
Roberts, Leslie G.
Sarwar, Husney Parvez
Commutative Algebra
13F15, 13F50, 13B02, 19D45
$(1)$ Let $M\subset N$ be a commutative cancellative torsion-free and subintegral extension of monoids. Then we prove that in the case of ring extension $A[M]\subset A[N]$, the two notions, subintegral and weakly subintegral coincide provided $\mathbb{Z}\subset A$. $(2)$ Let $A \subset B$ be an extension of commutative rings and $M\subset N$ an extension of commutative cancellative torsion-free positive monoids. Let $I$ be a radical ideal in $N$. Then $\frac{A[M]}{(I\cap M)A[M]}$ is subintegrally closed in $\frac{B[N]}{IB[N]}$ if and only if the group of invertible $A$-submodules of $B$ is isomorphic to the group of invertible $\frac{A[M]}{(I\cap M)A[M]}$-submodules of $\frac{B[N]}{IB[N]}$.
title Subintegrality and ideal class groups of monoid algebras
topic Commutative Algebra
13F15, 13F50, 13B02, 19D45
url https://arxiv.org/abs/2507.13845