Compact oracles for reachability and approximate distances in planar digraphs

  title={Compact oracles for reachability and approximate distances in planar digraphs},
  author={Mikkel Thorup},
  journal={Proceedings 2001 IEEE International Conference on Cluster Computing},
  • M. Thorup
  • Published 14 October 2001
  • Computer Science, Mathematics
  • Proceedings 2001 IEEE International Conference on Cluster Computing
It is shown that a planar digraph can be preprocessed in near-linear time, producing a near-linear space distance oracle that can answer reachability queries in constant time. The oracle can be distributed as an O(log n) space label for each vertex and then we can determine if one vertex can reach another considering their two labels only. The approach generalizes to approximate distances in weighted planar digraphs where we can then get a (1+/spl epsi/) approximation distance in O(log log /spl… 

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