I am dealing with a CVRP with multiple vehicles. I am struggling to come up with a formula for the constraint that each node with a non zero demand must be visited by one vehicle, once.
I am trying to enforce the constraint that if demand is greater than zero, than node visits by all vans is equal to $1$. Would the following suffice? $$\Large\boxed{max(d_i)\sum_{v\in V}y_i^v \ge d_i}$$
Assuming $d_i$ is the demand for node $i$ and $y_i^v$ is a binary decision variable that indicates whether node $i$ is visited by vehicle $v$, the desired constraint is $$\sum_v y_i^v = 1 \quad \text{for all $i$ such that $d_i>0$}$$