PTV Group - Logistics Forum

HI there,

one of my contacts faced the following error message triggered by a planVisitRequest:

Solver problem: No valid solution found.

He asked me about the cause of this error and here is some info:

• Cluster methods such as planVisits or planClusters try to identify a so-called "solution" which satisfies several threshold values, e.g. the imbalanceTolerance.
• Sometimes the algorithm is not able to find such a solution, either because the heuristic fails or because there is no such a solution.

Here are some examples for the "no valid solution found":

• planClusters: Try to cluster 3 customers with equal activity over 2 clusters with a balance <20%: if one cluster get's two customers and the other one get's just one the balance is 100% (from 1 to 2).
• planVisits: Try to plan 6 visits of 60mins on 5 weekdays with a balance <5%: if one day get's two visits while all other days get 1 visit the balance is 100% (from 1 to 2)

Depending on the activities you may have to increase the balance tolerance. With many cancidates (customers or visits) it is easier to consider a find a proper solution which satisfies the input balance.

Bernd