On path ranking in time-dependent graphs

In this paper we study a property of time-dependent graphs, dubbed “path ranking invariance”. Broadly speaking, graph is invariant” if the ordering its paths (w.r.t. travel time) independent start time. show that, path invariant, solution large class vehicle routing problems can be obtained by solving suitably defined (and simpler) time-independent problems. We also how checked linear program. If check fails, program used to determine tight lower bound. order assess value these insights, bounds have been embedded into an enumerative scheme. Computational results on versions Travelling Salesman Problem and Rural Postman that new findings enable outperform state-of-the-art algorithms.