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Value function
You will learn the basics of the value function on cloud.
The value function describes the optimization objective you're looking to minimize, maximize, or satisfy. For example, you may want to minimize time spent on the road for a routing problem or maximize employee wellness for a scheduling problem. The value function provides a way for Nextmv to numerically represent solution values (see below) and quantitatively compare them. Here, the term value function is equivalent to the term objective function and can include one or more business KPIs.
Currently, the Nextmv Cloud Dispatch app offers a default value function that minimizes time spent on the road measured in seconds. Additional value functions are also available on Nextmv Cloud depending on which properties you add to your input file, e.g., adding a vehicle initialization cost or earliness and lateness penalties will automatically update the default value function to include ETA error. Contact Nextmv to discuss support for other value functions on our cloud or SDK offerings.

Solution value

Solution values are numerical representations of the states a solver explores as part of an optimization problem. They are defined by the value function and can consist of several components.
For example, a solution value for the Dispatch app on Nextmv Cloud will seek to minimize time spent on the road in seconds. In this scenario, the solution value equals the total time spent on the road for all vehicles plus the total values for any defined penalties and vehicle initialization costs. The solver interprets lower solution values as better than higher solution values.
The JSON output provides value details at varying levels of granularity: by vehicle, by penalty, or as a summary.
JSON
{
...
"value_summary": {
// value summary
"value": 242799,
"total_travel_distance": 1207599.2080259852,
"total_travel_time": 67462.56991862402,
"total_earliness_penalty": 51723.25995969772,
"total_lateness_penalty": 23625.407207012177,
"total_unassigned_penalty": 0,
"total_vehicle_initialization_costs": 100000
}
...
}
Nextmv Cloud provides out-of-the-box visualizations for helping you to understand the breakdown of contributing factors to a solution value. For example, you may see that too many stops are going unassigned and adjustments to vehicle capacity or time windows are needed.
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