let R be a local ring, $\varphi$ $\in$ $End(R_{R}^{2})$, $\overline{\varphi}$ $\in$ $End($\overline{R}$_{\overline{R}}^{2})$ , $\overline{R}$ $=\frac{R}{J(R)}$ , J(R)= Jacobson radical R. where neither $\varphi$ nor $1-\varphi$  is invertible. why neither $\overline{\varphi}$ nor 1- $\overline{\varphi}$  is invertible in $End($\overline{R}$_{\overline{R}}^{2})$ ?