Improving the Price of Anarchy for Selfish Routing via Coordination Mechanisms

Christodoulou, George; Mehlhorn, Kurt; Pyrga, Evangelia

doi:10.1007/s00453-013-9753-8

Cited by 23 publications

(13 citation statements)

References 23 publications

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“…The impact of cost-sharing methods on the quality of equilibria has also been studied in other models: Moulin and Shenker [30] focused on participation games, while Moulin [29] and Mosk-Aoyama and Roughgarden [27] studied queueing games. Also, very closely related in spirit is previous work on coordination mechanisms, beginning with Christodoulou et al [9] and subsequently in [1,4,5,7,11,13,21,22]. Most work on coordination mechanisms concerns scheduling games and how the price of anarchy varies with the choice of local machine policies (i.e., the order in which to process jobs assigned to the same machine).…”

Section: Related Workmentioning

confidence: 92%

Cost-Sharing Methods for Scheduling Games under Uncertainty

Christodoulou

Gkatzelis

Sgouritsa

2017

Proceedings of the 2017 ACM Conference on Economics and Computation

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We study the performance of cost-sharing protocols in a selfish scheduling setting with load-dependent cost functions. Previous work on selfish scheduling protocols has focused on two extreme models: omnipotent protocols that are aware of every machine and every job that is active at any given time, and oblivious protocols that are aware of nothing beyond the machine they control. The main focus of this paper is on a well-motivated middle-ground model of resource-aware protocols, which are aware of the set of machines that the system comprises, but unaware of what jobs are active at any given time. Apart from considering budget-balanced protocols, to which previous work was restricted, we augment the design space by also studying the extent to which overcharging can lead to improved performance. We first show that, in the omnipotent model, overcharging enables us to enforce the optimal outcome as the unique equilibrium, which largely improves over the Θ(log n)-approximation of social welfare that can be obtained by budget-balanced protocols, even in their best equilibrium [32]. We then transition to the resource-aware model and provide price of anarchy (PoA) upper and lower bounds for different classes of cost functions. For concave cost functions, we provide a protocol with PoA of 1 + ϵ for arbitrarily small ϵ > 0. When the cost functions can be both convex and concave we construct an overcharging protocol that yields PoA≤ 2; a spectacular improvement over the bounds obtained for budget-balanced protocols, even in the omnipotent model. We complement our positive results with impossibility results for general increasing cost functions. We show that any resource-aware budget-balanced cost-sharing protocol has PoA of Θ(n) in this setting and, even if we use overcharging, no resource-aware protocol can achieve a PoA of o(√ n).

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Section: Related Workmentioning

confidence: 92%

Cost-Sharing Methods for Scheduling Games under Uncertainty

Christodoulou

Gkatzelis

Sgouritsa

2017

Proceedings of the 2017 ACM Conference on Economics and Computation

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“…The impact of cost-sharing methods on the quality of equilibria has also been studied in other models: Moulin and Shenker [2001] focused on participation games, while Moulin [2008] and Mosk-Aoyama and Roughgarden [2009] studied queueing games. Also, very closely related in spirit is previous work on coordination mechanisms, beginning with the work of Christodoulou et al [2009] and subsequently in the papers of Immorlica et al [2009], Azar et al [2015], Caragiannis [2013], Abed and Huang [2012], Kollias [2013], Cole et al [2015], Christodoulou et al [2014], Bhattacharya et al [2014]. Most work on coordination mechanisms concerns scheduling games and how the price of anarchy varies with the choice of local machine policies (i.e., the order in which to process jobs assigned to the same machine).…”

Section: Related Workmentioning

confidence: 94%

Resource-Aware Protocols for Network Cost-Sharing Games

Christodoulou

Gkatzelis

Latifian

et al. 2020

Proceedings of the 21st ACM Conference on Economics and Computation

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We study the extent to which decentralized cost-sharing protocols can achieve good price of anarchy (PoA) bounds in network cost-sharing games with n agents. We focus on the model of resource-aware protocols, where the designer has prior access to the network structure and can also increase the total cost of an edge (overcharging), and we study classes of games with concave or convex cost functions. We first consider concave cost functions and our main result is a cost-sharing protocol for symmetric games on directed acyclic graphs that achieves a PoA of 2+ε for some arbitrary small positive ε, which improves to 1 + ε for games with at least two players. We also achieve a PoA of 1 for series-parallel graphs and show that no protocol can achieve a PoA better than Ω(√ n) for multicast games. We then also consider convex cost functions and prove analogous results for series-parallel networks and multicast games, as well as a lower bound of Ω(n) for the PoA on directed acyclic graphs without the use of overcharging.

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“…In recent papers approaches to mitigate the Price of Anarchy have been proposed. Several approaches use coordination solutions to overcome the Price of Anarchy [20][21][22]. In Reference [23] the effects of user preference heterogeneity on the Price of Anarchy are analyzed.…”

Section: Routing Games and Selfish Routingmentioning

confidence: 99%

Shortest Paths from a Group Perspective—A Note on Selfish Routing Games with Cognitive Agents

Scholz

Church

2018

IJGI

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This paper presents an analysis of the effects of cognitive agents employing selfish routing behavior in traffic networks with linear latency functions. Selfish routing occurs when each agent traveling on a network acts in a purely selfish manner, therefore the Braess Paradox is likely to occur. The Braess Paradox describes a situation where an additional edge with positive capacity is added to a given network, which leads to higher total system delay. By applying the concept of cognitive agents, each agent is able to make a range of non-selfish and selfish decisions. In addition, each agent has to cope with uncertainty in terms of travel time information associated with the traffic system, a factor in real-world traffic networks. This paper evaluates the influence of travel time uncertainty, and possible non-selfish decisions of the agents on overall network delay. The results indicate that both non-selfish behavior and uncertainty have an influence on overall travel delay. In addition, understanding the influence of cognitive agents on delay can help to better plan and influence traffic flows resulting in “closer to optimal” flows involving overall lower delays.

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Improving the Price of Anarchy for Selfish Routing via Coordination Mechanisms

Cited by 23 publications

References 23 publications

Cost-Sharing Methods for Scheduling Games under Uncertainty

Cost-Sharing Methods for Scheduling Games under Uncertainty

Resource-Aware Protocols for Network Cost-Sharing Games

Shortest Paths from a Group Perspective—A Note on Selfish Routing Games with Cognitive Agents

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