Conditional switching between social excluders and loners promotes cooperation in spatial public goods game

We incorporate a conditional strategy that can switch between social excluders and loners in the spatial public goods game. Based on the number of defectors in the group compared to a controlled tolerance parameter, in-dividuals can adopt an excluder strategy to become excluders and expel the defectors, or adopt a loner strategy to become self-sufficient loners and refuse to participate in the game. By multi-agent-based simulation, we fully discuss the effect of conditional switching between these two different strategies on the cooperation level from the perspectives of tolerance parameter, exclusion cost, and exclusion probability respectively. Results show that the introduction of this conditional strategy can fully facilitate the evolution of cooperation, and the lower the tolerance parameter of the number of defectors in the group, the more conducive to the emergence of cooper-ation. However, when the tolerance parameter is high enough, the conditional strategy might not work under the effect of the exclusion cost and exclusion probability. Moreover, under the same tolerance parameter, the ad-vantages of smaller exclusion costs or the strengths of a larger exclusion probability in promoting cooperation are more pronounced. These results allow us to better understand the role of conditional strategy that switches between social excluders and loners in the evolution of cooperation.