51,688 research outputs found
Which Acceptable Agreements are Equilibria?
I propose a normal form game of agreement formation in which each player's strategy is to say for each size of agreement whether it is acceptable or not. I propose a refinement, which guarantees that each one of these choices is self-enforcing. For general payoff functions, which exhibit positive externalities, I analyse situations in which symmetric players have the possibility to reach a unique agreement. I prove the uniqueness of this equilibrium. I give two specific examples: a cartel and an agreement to contribute to a public good.coalition formation, normal form games, agreement, cartel, environmental agreement, public good
A Remark on Bargaining and Non-Expected Utility
We show that a bargaining game of alternating offers with exogenous risk of breakdown and played by dynamically consistent non-expected utility maximizers is formally equivalent to Rubinstein's (1982) game with time preference. Within this game, the behavior of dynamically consistent players is indistinguishable from the behavior of expected utility maximizers.Bargaining, non-expected utility.
Efficient Local Search in Coordination Games on Graphs
We study strategic games on weighted directed graphs, where the payoff of a
player is defined as the sum of the weights on the edges from players who chose
the same strategy augmented by a fixed non-negative bonus for picking a given
strategy. These games capture the idea of coordination in the absence of
globally common strategies. Prior work shows that the problem of determining
the existence of a pure Nash equilibrium for these games is NP-complete already
for graphs with all weights equal to one and no bonuses. However, for several
classes of graphs (e.g. DAGs and cliques) pure Nash equilibria or even strong
equilibria always exist and can be found by simply following a particular
improvement or coalition-improvement path, respectively. In this paper we
identify several natural classes of graphs for which a finite improvement or
coalition-improvement path of polynomial length always exists, and, as a
consequence, a Nash equilibrium or strong equilibrium in them can be found in
polynomial time. We also argue that these results are optimal in the sense that
in natural generalisations of these classes of graphs, a pure Nash equilibrium
may not even exist.Comment: Extended version of a paper accepted to IJCAI1
A Continuation Method for Nash Equilibria in Structured Games
Structured game representations have recently attracted interest as models
for multi-agent artificial intelligence scenarios, with rational behavior most
commonly characterized by Nash equilibria. This paper presents efficient, exact
algorithms for computing Nash equilibria in structured game representations,
including both graphical games and multi-agent influence diagrams (MAIDs). The
algorithms are derived from a continuation method for normal-form and
extensive-form games due to Govindan and Wilson; they follow a trajectory
through a space of perturbed games and their equilibria, exploiting game
structure through fast computation of the Jacobian of the payoff function. They
are theoretically guaranteed to find at least one equilibrium of the game, and
may find more. Our approach provides the first efficient algorithm for
computing exact equilibria in graphical games with arbitrary topology, and the
first algorithm to exploit fine-grained structural properties of MAIDs.
Experimental results are presented demonstrating the effectiveness of the
algorithms and comparing them to predecessors. The running time of the
graphical game algorithm is similar to, and often better than, the running time
of previous approximate algorithms. The algorithm for MAIDs can effectively
solve games that are much larger than those solvable by previous methods
Contributing or Free-Riding? Voluntary Participation in a Public Good Economy
We consider a (pure) public goods provision problem with voluntary participation in a quasi-linear economy. We propose a new hybrid solution concept, the free-riding-proof core (FRP-Core), which endogenously determines a contribution group, public good provision level, and its cost-sharing. The FRP-Core is always nonempty in public good economies but does not usually achieve global efficiency. The FRP-Core has support from both cooperative and noncooperative games. In particular, it is equivalent to the set of perfectly coalition-proof Nash equilibrium (Bernheim, Peleg, and Whinston, 1987) of a dynamic game with players' participation decisions followed by a common agency game of public goods provision. We illustrate various properties of the FRPCore with an example. We also show that the equilibrium level of public good shrinks to zero as the economy is replicated.endogenous coalition formation, externalities, public good, perfectly coalition-proof Nash equilibrium, free-riders, free-riding-proof core, lobbying, common agency game
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