Abstract
In this paper we consider the on-line version of the routing problem with release times. Formally, it consists in a metric space M with a distinguished point o (the origin), plus a sequence of triples<t i,pi,ri> where p i is a point of M, r i specifies the first moment in which the request is ready to be served, and t i represents the moment in which the request is known. A server located at point o at time 0 that moves at constant unit speed must serve the sequence of requests trying to minimize the total time till all the requests are served.
An on-line server follows a solution computed on the basis of the set of requests presented in the past; this solution may be updated each time some new piece of information is known. We show that no on-line algorithm, neither deterministic nor randomized, can achieve a competitive factor lower than 2. We give a 5/2-competitive exponential algorithm and a 3-competitive polynomial algorithm for the plane, and a 7/3-competitive algorithm for the line.
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This work was partly supported by ESPRIT BRA Alcom II under contract No.7141, and by Italian Ministry of Scientific Research Project 40% “Algoritmi, Modelli di Calcolo e Strutture Informative”.
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© 1994 Springer-Verlag Berlin Heidelberg
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Ausiello, G., Feuerstein, E., Leonardi, S., Stougie, L., Talamo, M. (1994). Serving requests with on-line routing. In: Schmidt, E.M., Skyum, S. (eds) Algorithm Theory — SWAT '94. SWAT 1994. Lecture Notes in Computer Science, vol 824. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-58218-5_4
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DOI: https://doi.org/10.1007/3-540-58218-5_4
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