I/O and Space-Efficient Path Traversal in Planar Graphs

  • Authors:
  • Craig Dillabaugh;Meng He;Anil Maheshwari;Norbert Zeh

  • Affiliations:
  • School of Computer Science, Carleton University, Canada;Cheriton School of Computer Science, University of Waterloo, Canada;School of Computer Science, Carleton University, Canada;Faculty of Computer Science, Dalhousie University, Canada

  • Venue:
  • ISAAC '09 Proceedings of the 20th International Symposium on Algorithms and Computation
  • Year:
  • 2009

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Abstract

We present a technique for representing bounded-degree planar graphs succinctly while permitting I/O-efficient path traversal. To represent a graph G on N vertices, each with an associated key of $q = O(\lg{N})$ bits, we use Nq + O(N) + o(Nq) bits. Using this representation, a path of length K can be traversed with $O(K/ \lg {B})$ I/Os, where B is the disk block size. Our structure may be adapted to represent, with similar space bounds, a terrain modeled as a triangular-irregular network to support traversal of a path that visits K triangles using $O(K/ \lg {B})$ I/Os. This structure can be used to answer a number of useful queries efficiently, such as reporting terrain profiles, trickle paths and connected components.