Figure 2: A co-ordinate system for describing strategies in public-goods games. | Scientific Reports

Figure 2: A co-ordinate system for describing strategies in public-goods games.

From: Small groups and long memories promote cooperation

Figure 2

We consider the space of strategies of the form , such that players cooperate with a probability that depends on the number of times lo her opponents have cooperated and the number of times lp she has cooperated within her memory. We define the strategy of a focal player by coordinates as shown in the figure. The components of this coordinate system have an intuitive interpretation: the probability that a player cooperates depends on (1) her past tendency to cooperate, (2) a baseline tendency to cooperate (κ), (3) a tendency to cooperate in proportion to her own payoff (χ), (4) a tendency to punish (i.e. defect) in proportion to her opponents’ payoffs (ϕ) and (5) a contingent punishment that depends on the specific outcome of the game over the prior m rounds ().

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