Title
Nashification and the coordination ratio for a selfish routing game
Abstract
We study the problem of n users selfishly routing traffic through a network consisting of m parallel related links. Users route their traffic by choosing private probability distributions over the links with the aim of minimizing their private latency. In such an environment Nash equilibria represent stable states of the system: no user can improve its private latency by unilaterally changing its strategy. Nashification is the problem of converting any given non-equilibrium routing into a Nash equilibrium without increasing the social cost. Our first result is an O(nm2) time algorithm for Nashification. This algorithm can be used in combination with any approximation algorithm for the routing problem to compute a Nash equilibrium of the same quality. In particular, this approach yields a PTAS for the computation of a best Nash equilibrium. Furthermore, we prove a lower bound of Ω(2√n) and an upper bound of O(2n) for the number of greedy selfish steps for identical link capacities in the worst case. In the second part of the paper we introduce a new structural parameter which allows us to slightly improve the upper bound on the coordination ratio for pure Nash equilibria in [3]. The new bound holds for the individual coordination ratio and is asymptotically tight. Additionally, we prove that the known upper bound of 1+√4m-3/2 on the coordination ratio for pure Nash equilibria also holds for the individual coordination ratio in case of mixed Nash equilibria, and we determine the range of m for which this bound is tight.
Year
DOI
Venue
2003
10.1007/3-540-45061-0_42
ICALP
Keywords
Field
DocType
mixed nash equilibrium,non-equilibrium routing,best nash equilibrium,pure nash equilibrium,coordination ratio,nash equilibrium,individual coordination ratio,selfish routing game,environment nash,approximation algorithm,private latency,probability distribution,upper bound,nash equilibria,it strategy,lower bound
Correlated equilibrium,Approximation algorithm,Mathematical optimization,Combinatorics,Epsilon-equilibrium,Strategy,Price of stability,Upper and lower bounds,Best response,Nash equilibrium,Mathematics
Conference
Volume
ISSN
ISBN
2719
0302-9743
3-540-40493-7
Citations 
PageRank 
References 
65
4.10
16
Authors
5
Name
Order
Citations
PageRank
Rainer Feldmann134436.63
Martin Gairing263347.14
Thomas Lücking335328.79
Burkhard Monien42199279.35
Manuel Rode519213.92