Issue
EPL
Volume 87, Number 4, August 2009
Article Number 48005
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/87/48005
Published online 07 September 2009
EPL, 87 (2009) 48005
DOI: 10.1209/0295-5075/87/48005

Imperfect imitation can enhance cooperation

C. P. Roca1, J. A. Cuesta1 and A. Sánchez1, 2, 3

1   GISC/Departamento de Matemáticas, Universidad Carlos III de Madrid - Madrid, Spain, EU
2   Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza - Zaragoza, Spain, EU
3   Instituto de Ciencias Matemáticas CSIC-UAM-UC3M-UCM - Madrid, Spain, EU

cproca@math.uc3m.es

received 1 June 2009; accepted in final form 6 August 2009; published August 2009
published online 7 September 2009

Abstract
The promotion of cooperation on spatial lattices is an important issue in evolutionary game theory. This effect clearly depends on the update rule: it diminishes with stochastic imitative rules whereas it increases with unconditional imitation. To study the transition between both regimes, we propose a new evolutionary rule, which stochastically combines unconditional imitation with another imitative rule. We find that, surprisingly, in many social dilemmas this rule yields higher cooperative levels than any of the two original ones. This nontrivial effect occurs because the basic rules induce a separation of timescales in the microscopic processes at cluster interfaces. The result is robust in the space of $2\times 2$ symmetric games, on regular lattices and on scale-free networks.

PACS
89.65.-s - Social and economic systems.
02.50.Le - Decision theory and game theory.
87.23.Kg - Dynamics of evolution.

© EPLA 2009