A new bidirectional search algorithm with shortened postprocessing |
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Authors: | Wim Pijls Henk Post |
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Institution: | 1. Erasmus University H10-20, Econometric Institute, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands;2. Connexxion Taxi Services, The Netherlands |
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Abstract: | For finding a shortest path in a network bidirectional A∗ is a widely known algorithm. This algorithm distinguishes between the main phase and the postprocessing phase. The version of bidirectional A∗ that is considered the most appropriate in literature hitherto, uses a so-called balanced heuristic estimate. This type of heuristic is chosen, as it accounts for a short postprocessing phase. In this paper, we do not restrict ourselves any longer to balanced heuristics. First, we introduce an algorithm containing a new method for the postprocessing phase, reducing this phase considerably for non-balanced heuristics. For a balanced heuristic the new algorithm is nearly equivalent to the existing versions of bidirectional A∗. An obvious choice for a non-balanced heuristic turns out to be superior in terms of storage space and computation time. Second, we show that the main phase on its own, when using this non-balanced heuristic estimate, is a useful algorithm, which provides us quickly with a feasible approximation. |
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Keywords: | Shortest path Road network search Bidirectional search |
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