Optimal location of transportation devices

  • Authors:
  • Jean Cardinal;Sébastien Collette;Ferran Hurtado;Stefan Langerman;Belén Palop

  • Affiliations:
  • Computer Science Department, Université Libre de Bruxelles CP 212, B-1050 Brussels, Belgium;Computer Science Department, Université Libre de Bruxelles CP 212, B-1050 Brussels, Belgium;Departament de Matemàtica Aplicada II, Universitat Politècnica de Catalunya Jordi Girona, 1--3, E-08034 Barcelona, Spain;Computer Science Department, Université Libre de Bruxelles CP 212, B-1050 Brussels, Belgium;Departamento de Informática, Universidad de Valladolid, Spain

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

We consider algorithms for finding the optimal location of a simple transportation device, that we call a moving walkway, consisting of a pair of points in the plane between which the travel speed is high. More specifically, one can travel from one endpoint of the walkway to the other at speed v1, but can only travel at unit speed between any other pair of points. The travel time between any two points in the plane is the minimum between the actual geometric distance, and the time needed to go from one point to the other using the walkway. A location for a walkway is said to be optimal with respect to a given finite set of points if it minimizes the maximum travel time between any two points of the set. We give a simple linear-time algorithm for finding an optimal location in the case where the points are on a line. We also give an @W(nlogn) lower bound for the problem of computing the travel time diameter of a set of n points on a line with respect to a given walkway. Then we describe an O(nlogn) algorithm for locating a walkway with the additional restriction that the walkway must be horizontal. This algorithm is based on a recent generic method for solving quasiconvex programs with implicitly defined constraints. It is used in a (1+@e)-approximation algorithm for optimal location of a walkway of arbitrary orientation.