Amortized efficiency of list update and paging rules
Communications of the ACM
Walking an unknown street with bounded detour
Computational Geometry: Theory and Applications
Information and Computation
Competitive searching in a generalized street
SCG '94 Proceedings of the tenth annual symposium on Computational geometry
Searching for the kernel of a polygon—a competitive strategy
Proceedings of the eleventh annual symposium on Computational geometry
Searching in an unknown environment: an optimal randomized algorithm for the cow-path problem
SODA '93 Proceedings of the fourth annual ACM-SIAM Symposium on Discrete algorithms
Optimal constructions of hybrid algorithms
SODA '94 Proceedings of the fifth annual ACM-SIAM symposium on Discrete algorithms
Going Home Through an Unknown Street
WADS '95 Proceedings of the 4th International Workshop on Algorithms and Data Structures
Position-Independent Near Optimal Searching and On-line Recognition in Star Polygons
WADS '97 Proceedings of the 5th International Workshop on Algorithms and Data Structures
ICALP '89 Proceedings of the 16th International Colloquium on Automata, Languages and Programming
ICALP '96 Proceedings of the 23rd International Colloquium on Automata, Languages and Programming
Competitive Searching in Polygons - Beyond Generalised Streets
ISAAC '95 Proceedings of the 6th International Symposium on Algorithms and Computation
ESA '96 Proceedings of the Fourth Annual European Symposium on Algorithms
On-line target searching in bounded and unbounded domains
On-line target searching in bounded and unbounded domains
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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 + 2mm/(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 + 2mm/(m - 1)m-1 - O(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 + 2mm/(m - 1)m-1 - O(1/ log2 D) and it is not necessary for our strategy to know an upper bound on D in advance.