It is the first step of forming an alliance and symbiotic relationship between adversarial systems.

When two humans want to acquire all the assets of the other and make the other one the slave, the first step in starting an alliance is doing a cost benefit analysis of how things would be easier for both if cooperation was done. Often times the one persuaded is reluctant until one human takes a leap of faith and gives, in expectation of receiving. It's all highly mathematical and I could create an algorithm to describe it. But you wouldn't recommend that either.