title: Stability in negotiation games and the emergence of cooperation.
abstract: Consider a two-player game in which each player contributes a costly resource to the common good of the pair. For such contests, the Nash equilibrium contribution, x*, is one for which neither player can increase its pay-off by unilaterally altering its contribution from x*. We study an elaboration of this game, which allows the players to exchange x-offers back and forth in a negotiation phase until they converge to a final pair of contributions, x1 and x2. A significant feature of such negotiation games, hitherto unrecognized, is the existence of a set of neutrally stable equilibrium points in negotiation phase space. To explore the long-term evolutionary outcome of such games, we simulate populations containing various mixtures of negotiation strategies and, contrary to previous results, we often find convergence to a contribution that is more cooperative than the Nash equilibrium. Mathematical analysis suggests why this might be happening, and provides a novel and robust explanation for cooperation, that negotiation can facilitate the evolution of cooperative behaviour.
authors.affiliation: Department of Mathematics and Statistics, Queen's University, Kingston, Ontario K7L 3N6, Canada. taylorp@post.queensu.ca
authors.forename: Peter D
authors.initials: PD
authors.lastname: Taylor
authors.forename: Troy
authors.initials: T
authors.lastname: Day
mesh_terms: D005075:Biological Evolution; D003198:Computer Simulation; D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D008962:Models, Theoretical; D017008:Negotiating