# Alliance formation with exclusion in the spatial public goods game

## TL;DR

This paper explores how unselfish exclusion strategies in structured populations can form alliances with cooperators to effectively eliminate defectors, even at high costs, revealing a potential evolutionary basis for extreme altruism.

## Contribution

It demonstrates that unselfish exclusion strategies can successfully form alliances with cooperators to suppress defectors, even when exclusion is highly costly.

## Key findings

- Unselfish exclusion strategies can eliminate defectors in structured populations.
- Alliances between cooperators and exclusion strategists are effective at high exclusion costs.
- Extreme altruism may emerge as an evolutionary strategy through alliance formation.

## Abstract

Detecting defection and alarming partners about the possible danger could be essential to avoid being exploited. This act, however, may require a huge individual effort from those who take this job, hence such a strategy seems to be unfavorable. But structured populations can provide an opportunity where a largely unselfish excluder strategy can form an effective alliance with other cooperative strategies, hence they can sweep out defection. Interestingly, this alliance is functioning even at the extremely high cost of exclusion where the sole application of an exclusion strategy would be harmful otherwise. These results may explain why the emergence of extreme selfless behavior is not necessarily against individual selection but could be the result of an evolutionary process.