Module Decompositions Using Pairwise Comaximal Ideals

Abstract

In this article, we show that for a given set of pairwise comaximal ideals {Xi}i∈I in a ring R with unity and any right R-module M with generating set Y and , M = ⊕i∈IC(Xi) if and only if for every y ∈ Y there exists a nonempty finite subset J ⊆ I and positive integers kj such that . We investigate this decomposition for a general class of modules. Our main theorem can be applied to a large class of rings including semilocal rings R with the Jacobson radical of R equal to the prime radical of R, left (or right) perfect rings, piecewise prime rings, and rings with ascending chain condition (ACC) on ideals and satisfying the right AR property on ideals. This decomposition generalizes the decomposition of a torsion abelian group into a direct sum of its p-components. We also develop a torsion theory associated with sets of pairwise comaximal ideals.