2010 | OriginalPaper | Buchkapitel
Fully Dynamic Speed-Up Techniques for Multi-criteria Shortest Path Searches in Time-Dependent Networks
verfasst von : Annabell Berger, Martin Grimmer, Matthias Müller-Hannemann
Erschienen in: Experimental Algorithms
Verlag: Springer Berlin Heidelberg
Aktivieren Sie unsere intelligente Suche, um passende Fachinhalte oder Patente zu finden.
Wählen Sie Textabschnitte aus um mit Künstlicher Intelligenz passenden Patente zu finden. powered by
Markieren Sie Textabschnitte, um KI-gestützt weitere passende Inhalte zu finden. powered by
We introduce two new speed-up techniques for time-dependent point-to-point shortest path problems with fully-dynamic updates in a multi-criteria setting. Our first technique, called SUBITO, is based on a specific substructure property of time-dependent paths which can be lower bounded by their minimal possible travel time. It requires no preprocessing, and the bounds can be computed on-the-fly for each query. We also introduce
k
-flags, an extension of arc flags, which assigns to each arc one of
k
levels for each region of a vertex partition. Intuitively, the higher the level of an arc for a certain destination, the larger the detour with respect to travel time.
k
-flags allow us to handle dynamic changes without additional time-consuming preprocessing.
In an extensive computational study using the train network of Germany we analyze these and other speed-up techniques with respect to their robustness under high and realistic update rates. We show that speed-up factors are conserved under different scenarios, namely a typical day of operation, distributed delays after “heavy snowfall”, and a major disruption at a single station. In our experiments,
k
-flags combined with SUBITO have led to the largest speed-up factors, but only marginally better than SUBITO alone. These observations can be explained by studying the distribution of
k
-flags. It turns out that only a small fraction of arcs can be excluded if one wants to guarantee exact Pareto-optimal point-to-point queries.