Example 1.12 Dynamic routing problems. In many routing problems such as
traveling salesman and vehicle routing problems, the properties of the input graph can
change over time concurrently with the search process. For the TSP, some cities may
be added or deleted during the tour. For the VRP, one can expect a new demand (new
customer) to be handled in the problem.Asolutionmight be regarded as a global optimal
solution at a given time and may not be optimal in the next time.