Abstract
We consider the problem of routing n users on m parallel links under the restriction that each user may only be routed on a link from a certain set of allowed links for the user. So, this problem is equivalent to the correspondingly restricted scheduling problem of assigning n jobs to m parallel machines. In a Nash equilibrium, no user may improve its own Individual Cost (latency) by unilaterally switching to another link from its set of allowed links.
For identical links, we present, as our main result, a polynomial time algorithm to compute from any given assignment a Nash equilibrium with non-increased makespan. The algorithm gradually transforms the assignment by pushing the unsplittable user traffics through a flow network, which is constructed from the users and the links. The algorithm uses ideas from blocking flows.
Furthermore, we use techniques simular to those in the generic PreflowPush algorithm to approximate in polynomial time a schedule with optimum makespan. This results to an improved approximation factor of \(2-\frac{1}{w_{1}}\) for identical links, where w 1 is the largest user traffic, and to an approximation factor of 2 for related links.
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A preliminary version of this work appeared in the Proceedings of the 36th Annual ACM Symposium on Theory of Computing, pp. 613–622, June 2004. This work has been partially supported by the IST Program of the European Union under contract numbers IST-1999-14186 ( \(\mathsf{ALCOM-FT}\) ), IST-2001-33116 ( \(\mathsf{FLAGS}\) ), 001907 ( \(\mathsf{DELIS}\) ) and 015964 ( \(\mathsf{AEOLUS}\) ). Parts of the work were done while the last author was visiting the Department of Computer Science, University of Cyprus. Research for this work was done while the first author was at the University of Paderborn.
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Gairing, M., Lücking, T., Mavronicolas, M. et al. Computing Nash Equilibria for Scheduling on Restricted Parallel Links. Theory Comput Syst 47, 405–432 (2010). https://doi.org/10.1007/s00224-009-9191-9
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DOI: https://doi.org/10.1007/s00224-009-9191-9