Szolnoki Attila, Perc Matjaž
Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, Hungarian Academy of SciencesP.O. Box 49, H-1525 Budapest, Hungary.
1] Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, SI-2000 Maribor, Slovenia [2] CAMTP - Center for Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor, Slovenia.
Sci Rep. 2014 Jun 30;4:5496. doi: 10.1038/srep05496.
We study the evolution of cooperation in the spatial prisoner's dilemma game, where besides unconditional cooperation and defection, tit-for-tat, win-stay-lose-shift and extortion are the five competing strategies. While pairwise imitation fails to sustain unconditional cooperation and extortion regardless of game parametrization, myopic updating gives rise to the coexistence of all five strategies if the temptation to defect is sufficiently large or if the degree distribution of the interaction network is heterogeneous. This counterintuitive evolutionary outcome emerges as a result of an unexpected chain of strategy invasions. Firstly, defectors emerge and coarsen spontaneously among players adopting win-stay-lose-shift. Secondly, extortioners and players adopting tit-for-tat emerge and spread via neutral drift among the emerged defectors. And lastly, among the extortioners, cooperators become viable too. These recurrent evolutionary invasions yield a five-strategy phase that is stable irrespective of the system size and the structure of the interaction network, and they reveal the most unexpected mechanism that stabilizes extortion and cooperation in an evolutionary setting.
我们研究空间囚徒困境博弈中合作的演变，其中除了无条件合作与背叛外，以牙还牙、赢留输变和敲诈勒索是五种相互竞争的策略。尽管无论博弈参数如何设定，两两模仿都无法维持无条件合作和敲诈勒索，但如果背叛的诱惑足够大，或者互动网络的度分布是异质的，近视更新会导致所有五种策略共存。这种违反直觉的进化结果是由一系列意想不到的策略入侵导致的。首先，背叛者在采用赢留输变的玩家中自发出现并聚集。其次，敲诈勒索者和采用以牙还牙策略的玩家在出现的背叛者中通过中性漂移出现并传播。最后，在敲诈勒索者中，合作者也变得可行。这些反复出现的进化入侵产生了一个五策略阶段，该阶段无论系统规模和互动网络结构如何都是稳定的，并且它们揭示了在进化环境中稳定敲诈勒索和合作的最意想不到的机制。
