\min {\sum_{i{\in}V}} {\sum_{j{\in}V \setminus \{i\} }} c_{ij} x_{ij} {\sum_{j{\in}V \setminus \{i\} }} x_{ij} = 1 \qquad \forall i \in V {\sum_{i{\in}V \setminus \{j\} }} x_{ij} = 1 \qquad \forall j \in V {\sum_{i{\in}S}} {\sum_{j{\in}V \setminus S }} x_{ij} \geq 1 \qquad \forall S \subset V x_{ij} \in \{0,1\} \qquad \forall (i,j) \in A