Minimum-link paths revisited

  • Authors:
  • Joseph S. B. Mitchell;Valentin Polishchuk;Mikko Sysikaski

  • Affiliations:
  • Department of Applied Mathematics and Statistics, Stony Brook University, United States;Helsinki Institute for Information Technology, Department of Computer Science, University of Helsinki, Finland and Communications and Transport Systems, ITN, Linköping University, Norrkö ...;Helsinki Institute for Information Technology, Department of Computer Science, University of Helsinki, Finland

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2014

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Abstract

A path or a polygonal domain is C-oriented if the orientations of its edges belong to a set of C given orientations; this is a generalization of the notable rectilinear case (C=2). We study exact and approximation algorithms for minimum-link C-oriented paths and paths with unrestricted orientations, both in C-oriented and in general domains. Our two main algorithms are as follows:A subquadratic-time algorithm with a non-trivial approximation guarantee for general (unrestricted-orientation) minimum-link paths in general domains. An algorithm to find a minimum-link C-oriented path in a C-oriented domain. Our algorithm is simpler and more time-space efficient than the prior algorithm. We also obtain several related results:*3SUM-hardness of determining the link distance with unrestricted orientations (even in a rectilinear domain). *An optimal algorithm for finding a minimum-link rectilinear path in a rectilinear domain. The algorithm and its analysis are simpler than the existing ones. *An extension of our methods to find a C-oriented minimum-link path in a general (not necessarily C-oriented) domain. *A more efficient algorithm to compute a 2-approximate C-oriented minimum-link path. *A notion of ''robust'' paths. We show how minimum-link C-oriented paths approximate the robust paths with unrestricted orientations to within an additive error of 1.