\begin{equation}
S_{p,\lambda}(\tau,j) = \left\{
\begin{split}
& \tau & \mbox{if}~ p \le \frac{\lambda}{3}\\
& \tau - \frac{j}{2}  & \mbox{if}~ \frac{\lambda}{3} < p \le \frac{2\lambda}{3}\\
& \tau - j & \mbox{if}~ p > \frac{2\lambda}{3}\\
\end{split}
\right.
\nonumber
\end{equation}
