Eur. Phys. J. B 44, 109-113 (2005)
https://doi.org/10.1140/epjb/e2005-00105-8

Economic demography in fuzzy spatial dilemmas and power laws

¹ Instituto de Física, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
² Instituto de Física, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo 11400, Uruguay

Corresponding author: ^a hugo@fisica.edu.uy

Received: 4 August 2004
Revised: 15 October 2004
Published online: 16 April 2005

Abstract

Adaptive agents, playing the iterated Prisoner's Dilemma (IPD) in a two-dimensional spatial setting and governed by Pavlovian strategies (“higher success-higher chance to stay”), are used to approach the problem of cooperation between self-interested individuals from a novel angle: We investigate the effect of different possible measures of success (MS) used by players to asses their performance in the game. These MS involve quantities such as: the player's utilities U, his cumulative score (or “capital”) W, his neighborhood “welfare”, etc. To handle an imprecise concept like “success” the agents use fuzzy logic. The degree of cooperation, the “economic demography” and the “efficiency” attained by the system depend dramatically on the MS. Specifically, patterns of “segregation” or “exploitation” are observed for some MS. On the other hand, power laws, that may be interpreted as signatures of critical self-organization (SOC), constitute a common feature for all the MS.