On the Complexity of Nash Equilibria of Action-Graph Games

Abstract. We consider the problem of computing Nash Equilibria of action-graph games (AGGs). AGGs, introduced by Bhat and Leyton-Brown, is a succinct representation of games that encapsulates both `local'dependencies as in graphical games, and partial indifference to other agents' identities as in anonymous games, which occur in many natural settings. This is achieved by specifying a graph on the set of actions, so that the payoff of an agent for selecting a strategy depends only on the number of agents playing each of the neighboring strategies in the action graph. We present a Polynomial Time Approximation Scheme for computing mixed Nash equilibria of AGGs with constant treewidth and a constant number of agent types (and an arbitrary number of strategies), together with hardness results for the cases when either the treewidth or the number of agent types is unconstrained. In particular, we show that even if the action graph is a tree, but the number of agent-types is uncons...

• Type: Journal
• Year: 2008
• Where: CORR
• Authors: Constantinos Daskalakis, Grant Schoenebeck, Gregory Valiant, Paul Valiant
• Keywords: Action Graph, CORR 2008, Education, Nash Equilibria, Polynomial Time Approximation Scheme