compg50_fast_dfix_T05.csv from The effect of network topology on optimal exploration strategies and the evolution of cooperation in a mobile population

We model a mobile population interacting over an underlying spatial structure using a Markov movement model. Interactions take the form of public goods games, and can feature an arbitrary group size. Individuals choose strategically to remain at their current location or to move to a neighbouring location, depending upon their exploration strategy and the current composition of their group. This builds upon previous work where the underlying structure was a complete graph (i.e. there was effectively no structure). Here, we consider alternative network structures and a wider variety of, mainly larger, populations. Previously, we had found when cooperation could evolve, depending upon the values of a range of population parameters. In our current work, we see that the complete graph considered before promotes stability, with populations of cooperators or defectors being relatively hard to replace. By contrast, the star graph promotes instability, and often neither type of population can resist replacement. We discuss potential reasons for this in terms of network topology.

本研究采用马尔可夫运动模型（Markov movement model），对基于潜在空间结构进行互动的移动种群开展建模。种群间的互动以公共品博弈（public goods game）形式展开，且可支持任意规模的群组。个体将基于自身的探索策略以及当前群组的组成情况，策略性选择停留在当前位置，或是迁移至邻近位置。该模型基于此前的研究工作搭建，彼时的潜在结构为完全图（complete graph，即本质上无空间结构）。本研究则考虑其他类型的网络结构，并针对更多样化（主要为更大规模）的种群展开分析。此前的研究发现，合作行为能否演化取决于一系列种群参数的取值。在本次研究中，我们发现此前采用的完全图结构能够提升系统稳定性，合作者或背叛者种群相对难以被替代。与之相反，星型图（star graph）则会加剧系统不稳定性，通常两类种群均难以抵御被替代的命运。我们将从网络拓扑（network topology）的角度，探讨产生这一现象的潜在原因。