论文标题

通过扩展分析SIRS过程的生存时间

Analysis of the survival time of the SIRS process via expansion

论文作者

Friedrich, Tobias, Göbel, Andreas, Klodt, Nicolas, Krejca, Martin S., Pappik, Marcus

论文摘要

我们研究SIRS过程,这是一种连续的马尔可夫链,对感染在图上的传播进行建模。在此模型中,顶点要么易感,感染或恢复。每个受感染的顶点以1的速率回收,并以$λ$独立地感染其易感邻居,并且每个回收的顶点都以$ \ varrho $的速度易感,我们假设这独立于图形大小。 SIRS过程的中心数量是直到未感染顶点的时间,称为生存时间。但是,令人惊讶的是,到目前为止相关的SIS模型仅存在严格的理论结果。 我们通过通过其扩展特性对SIR过程进行理论分析来解决这种不平衡。我们证明,对于$λ$的任何值,恒星上SIRS过程的预期生存时间最多是多项式的。这种行为与SIS过程根本不同,SIS过程的预期生存时间已经是小小的感染率的指数。 我们的主要结果是SIRS过程的预期生存时间的指数下限。具体来说,我们表明,在膨胀图上,$ n $顶点,接近$ d $的学位以及足够小的光谱扩展,Sirs Process预计生存时间至少在$ n $中的$λ\ geq c/d $ n $ n $ n $ n $ n $ n $。 SIS过程的先前结果表明,该界限几乎很紧。此外,即使$ g $是子图,我们的结果也会成立。值得注意的是,我们的结果意味着Erdos-rényi图的几乎密度阈值以及双曲随机图的指数生存时间。我们的主要结果的证明是从均值场理论中使用的lyapunov函数中汲取灵感,以设计二维潜在函数并应用负面的饮用定理,以表明预期的生存时间是指数级的。

We study the SIRS process, a continuous-time Markov chain modeling the spread of infections on graphs. In this model, vertices are either susceptible, infected, or recovered. Each infected vertex becomes recovered at rate 1 and infects each of its susceptible neighbors independently at rate $λ$, and each recovered vertex becomes susceptible at a rate $\varrho$, which we assume to be independent of the graph size. A central quantity of the SIRS process is the time until no vertex is infected, known as the survival time. Surprisingly though, rigorous theoretical results exist only for the related SIS model so far. We address this imbalance by conducting theoretical analyses of the SIRS process via their expansion properties. We prove that the expected survival time of the SIRS process on stars is at most polynomial in the graph size for any value of $λ$. This behavior is fundamentally different from the SIS process, where the expected survival time is exponential already for small infection rates. Our main result is an exponential lower bound of the expected survival time of the SIRS process on expander graphs. Specifically, we show that on expander graphs $G$ with $n$ vertices, degree close to $d$, and sufficiently small spectral expansion, the SIRS process has expected survival time at least exponential in $n$ when $λ\geq c/d$ for a constant $c > 1$. Previous results on the SIS process show that this bound is almost tight. Additionally, our result holds even if $G$ is a subgraph. Notably, our result implies an almost-tight threshold for Erdos-Rényi graphs and a regime of exponential survival time for hyperbolic random graphs. The proof of our main result draws inspiration from Lyapunov functions used in mean-field theory to devise a two-dimensional potential function and applying a negative-drift theorem to show that the expected survival time is exponential.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源