Title: Direct reciprocity and model-predictive strategy update explain the network reciprocity observed in socio-economic networks

Speaker: Fabio Dercole

Abstract:
Network reciprocity has been successfully put forward (since M.A. Nowak & R. May’s, 1992, influential paper) as the simplest mechanism — requiring no strategical complexity — supporting the evolution of cooperation in biological and socio-economic systems. The mechanism is actually the network, that makes agents’ interactions localized, while network reciprocity is the property of the underlying evolutionary process of favoring cooperation in sparse rather than dense networks. In theoretical models, the property holds under imitative evolutionary processes, that however lack rationality in the socio-economic context, whereas cooperation disappears in any network if imitation is replaced by the more rational best-response rule of strategy update. In social experiments, network reciprocity has been observed, though the imitative behavior did not emerge. What did emerge is a form of conditional cooperation based on direct reciprocity—the propensity to cooperate with neighbors who previously cooperated. To resolve this inconsistency, we show network reciprocity in a model that
rationally confronts the two main behaviors emerging in experiments — reciprocal cooperation and unconditional defection — with rationality introduced by means of a multi-step model-predictive rule for strategy update.

Sala de Conferencias, Edif. I+D, Campus Rio Ebro
LUNES 10 de FEBRERO a las 12:30h