Designing Network Protocols for Good Equilibria

13 years 2 months ago

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Designing and deploying a network protocol determines the rules by which end users interact with each other and with the network. We consider the problem of designing a protocol to optimize the equilibrium behavior of a network with selﬁsh users. We consider network costsharing games, where the set of Nash equilibria depends fundamentally on the choice of an edge cost-sharing protocol. Previous research focused on the Shapley protocol, in which the cost of each edge is shared equally among its users. We systematically study the design of optimal cost-sharing protocols for undirected and directed graphs, single-sink and multicommodity networks, and diﬀerent measures of the ineﬃciency of equilibria. Our primary technical tool is a precise characterization of the cost-sharing protocols that only induce network games with pure-strategy Nash equilibria. We use this characterization to prove, among other results, that the Shapley protocol is optimal in directed graphs, and that simple...

Ho-Lin Chen, Tim Roughgarden, Gregory Valiant

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