标题： 大型独立代理系统中的分层噪声 显示英文标题

标题： Hierarchical noise in large systems of independent agents

摘要： 一种相干噪声模型的推广 [M. E. J. Newman 和 K. Sneppen, Phys. Rev. E{\bf 54}, 6226 (1996)] 被提出，其中模型中的代理受到多种应力的作用，这些应力在不同背景的层次结构中产生。该层次结构被实现为一个Cayley树。考虑了树中应力传播的两种不同方式。在两种情况下，树的大子系统中都会出现相干性。可以观察到树模型和相干噪声模型的行为有明显的相似之处。对于两种应力传播方法中的一种，树模型的行为可以很好地由一组相干噪声模型来近似，其中集合中系统的大小$k$按照$k^{-2}$进行缩放。结果发现，对于大量合理的选择，结果与树的结构无关。此外，发现即使在代理所感受到的应力之间完全没有相关性的情况下，代理的寿命也会出现幂律分布。 显示英文摘要

摘要： A generalization of the coherent-noise models [M. E. J. Newman and K. Sneppen, Phys. Rev. E{\bf54}, 6226 (1996)] is presented where the agents in the model are subjected to a multitude of stresses, generated in a hierarchy of different contexts. The hierarchy is realized as a Cayley-tree. Two different ways of stress propagation in the tree are considered. In both cases, coherence arises in large subsystems of the tree. Clear similarities between the behavior of the tree model and of the coherent-noise model can be observed. For one of the two methods of stress propagation, the behavior of the tree model can be approximated very well by an ensemble of coherent-noise models, where the sizes $k$ of the systems in the ensemble scale as $k^{-2}$. The results are found to be independent of the tree's structure for a large class of reasonable choices. Additionally, it is found that power-law distributed lifetimes of agents arise even under the complete absence of correlations between the stresses the agents feel.