论文标题
动态网络中平滑模型
Models of Smoothing in Dynamic Networks
论文作者
论文摘要
平滑分析是一种框架,用于介导最坏情况和平均案例复杂性之间的差距。在最近的工作中,Dinitz等人〜[分布式计算,2018年]建议使用平滑的分析来研究动态网络。他们的目的是解释尽管动态动态,但在任意网络的强大理论下限中,现实世界网络之间的差距。为此,他们在动态网络中引入了平滑的基本模型,在该网络中,对手选择了一系列图,代表网络的拓扑随着时间的推移,然后以随机方式稍微扰动这些图。上面建议的模型基于每轮噪声,我们在这项工作中的目的是将其扩展到更适合多个回合的噪声模型。这是由长期寿命的网络激励的,噪声的数量和位置可能会随着时间而变化。为此,我们提出了几种不同的噪声模型。首先,我们将先前的模型扩展到噪声量很小的情况。然后,我们移动到更精致的模型,其中噪声量可以在不同的回合之间发生变化,例如,作为网络经历的变化数量的函数。我们还研究了一个模型,其中噪声不是任意传播在网络之间的模型,而是在发生变化的区域中的每个回合。最后,我们研究了自适应对手的力量,他可以根据迄今为止发生的变化选择其行动。我们将洪水问题用作运行的案例研究,在不同的噪声模型下呈现截然不同的行为,并在不同模型中分析洪水时间。
Smoothed analysis is a framework suggested for mediating gaps between worst-case and average-case complexities. In a recent work, Dinitz et al.~[Distributed Computing, 2018] suggested to use smoothed analysis in order to study dynamic networks. Their aim was to explain the gaps between real-world networks that function well despite being dynamic, and the strong theoretical lower bounds for arbitrary networks. To this end, they introduced a basic model of smoothing in dynamic networks, where an adversary picks a sequence of graphs, representing the topology of the network over time, and then each of these graphs is slightly perturbed in a random manner. The model suggested above is based on a per-round noise, and our aim in this work is to extend it to models of noise more suited for multiple rounds. This is motivated by long-lived networks, where the amount and location of noise may vary over time. To this end, we present several different models of noise. First, we extend the previous model to cases where the amount of noise is very small. Then, we move to more refined models, where the amount of noise can change between different rounds, e.g., as a function of the number of changes the network undergoes. We also study a model where the noise is not arbitrarily spread among the network, but focuses in each round in the areas where changes have occurred. Finally, we study the power of an adaptive adversary, who can choose its actions in accordance with the changes that have occurred so far. We use the flooding problem as a running case-study, presenting very different behaviors under the different models of noise, and analyze the flooding time in different models.