Departament d'Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, 43007 Tarragona, Spain.
J Theor Biol. 2011 Jun 21;279(1):113-9. doi: 10.1016/j.jtbi.2011.03.017. Epub 2011 Mar 31.
Understanding the emergence of cooperation is a central issue in evolutionary game theory. The hardest setup for the attainment of cooperation in a population of individuals is the Public Goods game in which cooperative agents generate a common good at their own expenses, while defectors "free-ride" this good. Eventually this causes the exhaustion of the good, a situation which is bad for everybody. Previous results have shown that introducing reputation, allowing for volunteer participation, punishing defectors, rewarding cooperators or structuring agents, can enhance cooperation. Here we present a model which shows how the introduction of rare, malicious agents--that we term jokers--performing just destructive actions on the other agents induce bursts of cooperation. The appearance of jokers promotes a rock-paper-scissors dynamics, where jokers outbeat defectors and cooperators outperform jokers, which are subsequently invaded by defectors. Thus, paradoxically, the existence of destructive agents acting indiscriminately promotes cooperation.
理解合作的出现是进化博弈论中的一个核心问题。在个体群体中实现合作的最困难设置是公共物品博弈，其中合作的代理人以自己的代价产生共同利益，而叛徒“搭便车”利用这个好处。最终，这会导致利益的枯竭，这种情况对每个人都不利。之前的研究结果表明，引入声誉、允许自愿参与、惩罚叛徒、奖励合作者或构建代理，可以增强合作。在这里，我们提出了一个模型，展示了引入稀有、恶意的代理人——我们称之为小丑——只对其他代理人进行破坏性的行为，如何诱导合作的爆发。小丑的出现促进了一种石头剪刀布的动态，其中小丑胜过叛徒，合作者胜过小丑，而小丑随后被叛徒入侵。因此，矛盾的是，破坏性代理人的存在不分青红皂白地促进了合作。
