Relative torsionfreeness and Frobenius extensions

Yanhong Bao, Jiafeng Lü, Zhibing Zhao

Let $S/R$ be a Frobenius extension with ${}_R{S}_R$ centrally projective over $R$. We show that if ${}_R\ddot{I}‰$ is a Wakamatsu tilting module then so is ${}_{S}S{\otimes }_R\ddot{I}‰$, and the natural rin…