The Ultimate Strategy to Search on m Rays?

  • Alejandro López-Ortiz
  • Sven Schuierer
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1449)


We consider the problem of searching on m current rays for a target of unknown location. If no upper bound on the distance to the target is known in advance, then the optimal competitive ratio is 1 + 2m m/(m − 1)m−1. We show that if an upper bound of D on the distance to the target is known in advance, then the competitive ratio of any searchst rategy is at least 1 + 2m m/(m − 1)m−1O(1/log2 D) which is also optimal—but in a stricter sense.

We also construct a search strategy that achieves this ratio. Astonishingly, our strategy works equally well for the unbounded case, that is, if the target is found at distance D from the starting point, then the competitive ratio is 1 + 2m m/(m − 1)m−1O(1/log2 D) and it is not necessary for our strategy to know an upper bound on D in advance.


Search Strategy Optimal Strategy Recurrence Equation Competitive Ratio Positive Real Root 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Alejandro López-Ortiz
    • 1
  • Sven Schuierer
    • 2
  1. 1.Faculty of Computer ScienceUniversity of New BrunswickCanada
  2. 2.Institut für InformatikUniversität FreiburgFreiburgFRG

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