Individual wealth-based selection supports cooperation in spatial public goods games

TL;DR

This paper introduces a model combining probabilistic participation with wealth-based criteria in spatial public goods games, demonstrating that wealth thresholds enhance cooperation and network reciprocity.

Contribution

It presents a novel wealth-based participation rule that significantly promotes cooperation in spatial public goods games beyond existing probabilistic models.

Findings

Wealth-based participation expands the parameter space for cooperation.

Structured populations outperform well-mixed ones with wealth criteria.

Network reciprocity is notably enhanced by wealth thresholds.

Abstract

In a social dilemma game group members are allowed to decide if they contribute to the joint venture or not. As a consequence, defectors, who do not invest but only enjoy the mutual benefit, prevail and the system evolves onto the tragedy of the common state. This unfortunate scenario can be avoided if participation is not obligatory but only happens with a given probability. But what if we also consider a player's individual wealth when to decide about participation? To address this issue we propose a model in which the probabilistic participation in the public goods game is combined with a conditional investment mode that is based on individual wealth: if a player's wealth exceeds a threshold value then it is qualified and can participate in the joint venture. Otherwise, the participation is forbidden in the investment interactions. We show that if only probabilistic participation is considered, spatially structured populations cannot support cooperation better than well-mixed populations where full defection state can also be avoided for small participation probabilities. By adding the wealth-based criterion of participation, however, structured populations are capable to augment network reciprocity relevantly and allow cooperator strategy to dominate in a broader parameter interval.