Adoption of simultaneous different strategies against different opponents enhances cooperation

Departamento de Física, Universidade Federal de Minas Gerais - Caixa Postal 702, CEP 30161-970, Belo Horizonte, MG, Brazil

Corresponding authors: wardil@fisica.ufmg.br jaff@fisica.ufmg.br

Received: 12 February 2009
Accepted: 14 April 2009

Abstract

The emergence of cooperation has been widely studied in the context of game theory on structured populations. Usually the individuals adopt one strategy against all their neighbors. The structure can provide reproductive success for the cooperative strategy, at least for low values of defection tendency. Other mechanisms, such as punishment, can also be responsible for cooperation emergence. But what happens if the players adopt simultaneously different strategies against each one of their opponents, not just a single one? Here we study this question in the prisoner dilemma scenario structured on a square lattice and on a ring. We show that if an update rule is defined in which the players replace the strategy that furnishes the smallest payoff, a punishment response mechanism against defectors without imputing cost to the punishers appears, cooperation dominates and, even if the tendency of defection is huge, cooperation still remains alive.