The evolution of cooperation in spatial public goods games under a risk-transfer mechanism

An interest coalition of sharing benefits and risks, such as cross shareholding between companies, allows them to transfer risks in a competitive business world. In a public goods game, cooperators are at the risk of being exploited by defectors. This paper studies whether such risk-transfer mechanism can induce cooperative be-haviors in social dilemmas. We model a public goods game with coalition mechanism in a structured population. The players are categorized by whether they cooperate as well as whether they are willing to form coalitions. Those who are willing (unwilling) to form coalitions with others are called coalitional (traditional) individuals. By exploring the phase transitions of systems, the spatial dynamics of some phases and the evolution of char-acteristic spatial distributions of strategies, we study the effect of this mechanism on cooperation. The results show that the positive (negative) impact of such interest coalitions on the competitiveness of cooperators (de-fectors) can be improved as the closeness of interest relationship within coalitions increases. However, this does not mean that a closer coalition can absolutely increase the overall level of cooperation in a more complex four -strategy system. This is related to the transformation from CCs (coalitional cooperators) to TDs (traditional defectors) due to CCs' breaking of the encirclement formed by CDs (coalitional defectors) at a low synergy co-efficient, as well as the invasion of TCs (traditional cooperators) to CCs at the boundary separating CCs, TCs and TDs at a high synergy coefficient.