\begin{equation}
x_{i j} = \left\{
\begin{array}{l}
1, \text{ 如果第 } i \text{ 个部门迁往第 } j \text{ 个城市} \\
0, \text{ 否则}
\end{array}
\right.
\end{equation}
显示效果:
\begin{equation*}
\begin{aligned}
&\left\{
\begin{array}{l}
\sum_{j=1}^{3} X_{ij} = 1, \quad i=1,2,3,4,5 \\
\sum_{i=1}^{5} X_{ij} \leq 3, \quad j=1,2,3 \\
X_{ij} \in \{0, 1\}
\end{array}
\right.
\end{aligned}
\end{equation*}
显示效果:
如果想叫s.t.
\begin{equation*}
\begin{aligned}
s.t. \left\{
\begin{array}{l}
\sum_{j=1}^{3} X_{ij} = 1, \quad i=1,2,3,4,5 \\
\sum_{i=1}^{5} X_{ij} \leq 3, \quad j=1,2,3 \\
Y_{ijkl} - X_{ij} \leq 0,\quad j,l=1,2,3 \quad i,k=1,2,3,k>i\\
Y_{ijkl} - X_{kl} \leq 0, \quad j,l=1,2,3 \quad i,k=1,2,3,k>i \\
X_{ij}+X_{kl}-Y_{ijkl}-1 \leq 0, \quad j,l=1,2,3 \quad i,k=1,2,3,k>i \\
X_{ij} \in \{0, 1\}\quad i=1,2,3,4,5\quad j=1,2,3\\
Y_{ijkl} \in \{0, 1\}\quad i,k=1,2,3,4,5\quad j,l=1,2,3\\
\end{array}
\right.
\end{aligned}
\end{equation*}
显示效果: