Fast convergence to nearly optimal solutions in potential games

Baruch Awerbuch, Yossi Azar, Amir Epstein, Vahab Seyed Mirrokni, Alexander Skopalik
2008 Proceedings of the 9th ACM conference on Electronic commerce - EC '08  
We study the speed of convergence of decentralized dynamics to approximately optimal solutions in potential games. We consider α-Nash dynamics in which a player makes a move if the improvement in his payoff is more than an α factor of his own payoff. Despite the known polynomial convergence of α-Nash dynamics to approximate Nash equilibria in symmetric congestion games [7] , it has been shown that the convergence time to approximate Nash equilibria in asymmetric congestion games is exponential
more » ... 23]. In contrast to this negative result, and as the main result of this paper, we show that for asymmetric congestion games with delay functions that satisfy a "bounded jump" condition, the convergence time of α-Nash dynamics to an approximate optimal solution is polynomial in the number of players, with approximation ratio that is arbitrarily close to the price of anarchy of the game. In particular, we show this polynomial convergence under the minimal liveness assumption that each player gets at least one chance to move in every T steps. We also prove that the same polynomial convergence result does not hold for (exact) best-response dynamics, showing the α-Nash dynamics is required. We extend these results for congestion games to other potential games including weighted congestion games with linear delay functions, cut games (also called party affiliation games) and market sharing games as follows.
doi:10.1145/1386790.1386832 dblp:conf/sigecom/AwerbuchAEMS08 fatcat:7gwjunsbbrdzvpf5f6yxgd5fha