arXivDaily arXiv每日学术速递 周一至周五更新
arXiv math/0311125math.PRmath.GR
收藏

无限树和非amenable groups上的Bootstrap渗流

Bootstrap percolation on infinite trees and non-amenable groups

Jozsef Balogh, Yuval Peres, Gabor Pete

摘要:

在任意图上的自举渗透有一个随机的初始配置,其中每个顶点被占据的概率为p,彼此独立,和一个确定性的扩散规则,具有固定的参数k:如果一个空位在某个时间步至少有k个被占据的邻居,那么它在下一个步骤中被占据。这个过程在Z^d上已经得到了很好的研究;在这里,我们在正则无限树和一般无限树以及不服从的凯莱图上研究它。临界概率是过程以正概率完全占据的p值的下确界。在一般的树上,我们发现了如下的不连续性:如果树的分支数严格小于k,则临界概率为1,而在k元树上,临界概率为1-1/k。一个相关的结果是,在任何有根树T中,有一种方法可以擦除根的k个孩子以及它们的所有后代,并对所有剩余的孩子重复这一过程,以此类推,使得剩余的树T'具有分支数\br(T')\leq \max(\br(T)-k,0)。我们还证明了在任何2k-正则非顺从图上,k-规则的临界概率是严格正的。

英文摘要:

Bootstrap percolation on an arbitrary graph has a random initial configuration, where each vertex is occupied with probability p, independently of each other, and a deterministic spreading rule with a fixed parameter k: if a vacant site has at least k occupied neighbors at a certain time step, then it becomes occupied in the next step. This process is well-studied on Z^d; here we investigate it on regular and general infinite trees and on non-amenable Cayley graphs. The critical probability is the infimum of those values of p for which the process achieves complete occupation with positive probability. On general trees, we find the following discontinuity: if the branching number of a tree is strictly smaller than k, then the critical probability is 1, while it is 1-1/k on the k-ary tree. A related result is that in any rooted tree T, there is a way of erasing k children of the root, together with all their descendants, and repeating this for all remaining children, and so on, such that the remaining tree T' has branching number \br(T') \leq \max (\br(T)-k, 0). We also prove that on any 2k-regular non-amenable graph, the critical probability for the k-rule is strictly positive.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑