The problem is to determine the corresponding vehicle routes so as to minimize the total cost subject to the following assumptions:
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Each vehicle is used for at most one route.
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Each route starts and ends at the depot.
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Each customer is served by exactly one vehicle.
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Fuel level at the vehicle's tank must be greater than or equal to the fuel consumption between any two nodes.
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The amount of fuel in a vehicle's tank is sufficient to be able to visit between any pair of nodes.
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The duration of the route assigned to a vehicle cannot exceed Tmax.