define $\displaystyle R=\mathbb{Q}G$ where $\displaystyle G=<g>$ is a cyclic group of prime order p, then R is a module over itself (it's a ring). If $\displaystyle x=\sum g^i$ then I need to show that the set $\displaystyle \{y\in R \mid xy=0\}$ is an indecomposable module.