 (R/{\mathfrak{c}})^{\oplus 0} \overset{ \begin{pmatrix} -\overline{b} & \overline{a}\\ -\overline{c} & \overline{b} \end{pmatrix}}{\longrightarrow} (R/{\mathfrak{c}})^{\oplus 0} \overset{ \begin{pmatrix} -\overline{b} & \overline{a}\\ -\overline{c} & \overline{b} \end{pmatrix}}{\longrightarrow} (R/{\mathfrak{c}})^{\oplus 0} 