\begin{equation}
prob=\left\{
\begin{array}{cc}\frac{{| s_{i}|}^\alpha{\[ \eta_{i}\]}^\b}{\sum {|s_{i}|}^\alpha{\[ \eta_{i}\]}^\b} \text{$ j\epsilon$ ~route} \\ 0 \mbox{otherwise}
\right\}.
\end{array}
\end{equation}
我在方程中遇到了错误
\begin{equation}
prob=\left\{
\begin{array}{cc}\frac{{| s_{i}|}^\alpha{\[ \eta_{i}\]}^\b}{\sum {|s_{i}|}^\alpha{\[ \eta_{i}\]}^\b} \text{$ j\epsilon$ ~route} \\ 0 \mbox{otherwise}
\right\}.
\end{array}
\end{equation}