Milk Collection: How to Route and Assign Milk Collection Lorries to Farms

Table 23.2 shows the parameters that are used in this example.

Table 23.2: Parameters

Parameter Name	Interpretation
east[i]	East coordinate of node i
north[i]	North coordinate of node i
frequency[i]	Number of times node i must be visited (1 for every other day, 2 for every day)
requirement[i]	Collection requirement of node i (in 1,000 litres)
distance[i,j]	Distance between nodes i and j (in miles)
distance_scale	Distance scale
num_days	Number of days in planning horizon
capacity	Capacity of the lorry (in 1,000 litres)
depot	Node number of depot
num_subtours	Number of subtours in current formulation
iter	Iteration number for each round of subtour elimination constraints
num_components[d]	Number of connected components in solution for day d
component_id[i]	Connected component containing node i
ci,cj	Dummy indices for members of COMPONENT_IDS