Reversibility of a module with respect to the bifunctors Hom and‎ ‎Rej

Document Type : Research Paper


1 Isfahan University of Technology

2 Department of of Mathematical Sciences, Isfahan University of Technology, Isfahan 84156-83111,


Let $M_R$ be a non-zero‎
‎module and ${\mathcal F}‎: ‎\sigma[M_R]\times \sigma[M_R]‎
‎\rightarrow$ Mod-$\Bbb{Z}$ a bifunctor‎. ‎The‎
‎$\mathcal{F}$-reversibility of $M$ is defined by ${\mathcal‎
‎F}(X,Y)=0 \Rightarrow {\mathcal F}(Y,X)=0$ for all non-zero $X,Y$‎
‎in $\sigma[M_R]$‎. ‎Hom (resp‎. ‎Rej)-reversibility of $M$ is‎
‎characterized in different ways‎. ‎Among other things‎, ‎it is shown‎
‎that $R_R$ {\rm($_RR$)} is Hom-reversible if and only if $R =‎
‎\bigoplus_{i=1}^n R_i$ such that each $R_i$ is a perfect ring with‎
‎a unique simple module (up to isomorphism)‎. ‎In particular‎, ‎for a‎
‎duo ring‎, ‎the concepts of perfectness and Hom-reversibility‎


Main Subjects