Shortest paths without a map

Extended abstract
  • Christos H. Papadimitriou
  • Mihalis Yannakakis
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 372)


We study several versions of the shortest-path problem when the map is not known in advanced, but is specified dynamically. We are seeking dynamic decision rules that optimize the worst-case ratio of the distance covered to the length of the (statically) optimal path. We describe optimal decision rules for two cases: Layered graphs of bounded width, and two-dimensional scenes with unit square obstacles. The optimal rules turn out to be intuitive, common-sense heuristics. For slightly more general graphs and scenes, we show that no bounded ratio is possible. We also show that the computational problem of devising a strategy that achieves a given worst-case ratio to the optimum path in a graph is a universal two-person game, and thus PSPACE-complete, whereas optimizing the expected ratio is #P-hard.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Christos H. Papadimitriou
    • 1
  • Mihalis Yannakakis
    • 2
  1. 1.Department of Computer Science and EngineeringUniversity of California at San DiegoUSA
  2. 2.AT&T Bell LaboratoriesUSA

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