Querying Two Boundary Points for Shortest Paths in a Polygonal Domain

  • Authors:
  • Sang Won Bae;Yoshio Okamoto

  • Affiliations:
  • Department of Computer Science and Engineering, POSTECH, Pohang, Korea;Graduate School of Information Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan

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

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Abstract

We consider a variant of two-point Euclidean shortest path query problem: given a polygonal domain, build a data structure for two-point shortest path query, provided that query points always lie on the boundary of the domain. As a main result, we show that a logarithmic-time query for shortest paths between boundary points can be performed using $\tilde{O}(n^5)$ preprocessing time and $\tilde{O}(n^5)$ space where n is the number of corners of the polygonal domain and the $\tilde{O}$-notation suppresses the polylogarithmic factor. This is realized by observing a connection between Davenport-Schinzel sequences and our problem in the parameterized space. We also provide a tradeoff between space and query time; a sublinear time query is possible using O(n 3 + 驴 ) space. Our approach also extends to the case where query points should lie on a given set of line segments.