I've seen constraint solvers used in a couple of contexts. The first was at a food delivery company where we used one to calculate optimal delivery routes - we

I've seen constraint solvers used in a couple of contexts. The first was at a food delivery company where we used one to calculate optimal delivery routes - we'd give it a list of delivery vans available, and a list of deliveries with the distances between those deliveries, along with constraints such as the size of the delivery to be made and capacity of the vans, and the desired delivery times. With that information it would then determine which van deliveries should be in, and what order they should be made in. The second was a large conference, where it was used to work out the talk schedule given a list of talks, a list of available venues, and any requirements for each talk such as a venue of a certain size, or the need for a projector. It took a while to work things out, but eventually it would either find slots for everyone, or determine that it was impossible to schedule everything within the given constraints. (For the curious it can be found here: https://github.com/emfcamp/slotmachine https://github.com/emfcamp/slotmachine)