Non-zero-sum games are strategic interactions between adaptive agents where the outcome has net results greater or less than zero. A non-zero-sum game is a situation where participants are interdependent, being able to all gain or suffer together. For example, economic trade is believed to be positive-sum, because when two parties agree to an exchange each party must consider the goods it is receiving to be more valuable than the goods it is delivering, this type of positive sum game is a strong driver towards cooperation; as the pie gets bigger and everyone gets higher payoffs by simply interacting. Thus with non-zero-sum games, a gain by one agent does not necessarily correspond with a loss by another. Equally non-zero-sum games may be negative-sum, meaning everyone looses, an arms race may be an example of this. Problems in the real world are typically non-zero-sum, where there is no single optimal strategy that is preferable to all others, nor is there a predictable outcome. Players engaged in a non-zero sum conflict have both some complementary interests and some interests that are opposed, thus they are complex.