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arXiv 1107.0079math.PR
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临界多型分枝系统:灭绝结果

Critical Multitype Branching Systems: Extinction Results

Peter Kevei, Jose Alfredo Lopez Mimbela

摘要:

我们考虑$\R^d$中的一个临界分支粒子系统,它由有限个类型$i\in\{1,...,K\}$的个体组成。每个$i$型个体根据对称的$α_i$稳定运动独立移动。我们假设粒子的寿命和后代分布是依赖于类型的。在分支系统中通常的独立性假设下,证明了如下情形的灭绝定理:(1)所有粒子的寿命都有有限平均,或(2)存在一种粒子的寿命分布有重尾,而其它粒子的寿命都有有限平均.在情形(2)中,我们假设最具移动性的粒子类型对应于有限平均寿命,从而得到更复杂的动力学:在这种情形中,种群的局部灭绝是由长寿型和最具移动性的粒子类型的参数(后代变异性、移动性、寿命)的相互作用决定的。的证据是基于一个精确的分析的占领时间相关的马尔可夫更新过程,这是独立的利益。

英文摘要:

We consider a critical branching particle system in $\R^d$, composed of individuals of a finite number of types $i\in\{1,...,K\}$. Each individual of type $i$ moves independently according to a symmetric $α_i$-stable motion. We assume that the particle lifetimes and offspring distributions are type-dependent. Under the usual independence assumptions in branching systems, we prove extinction theorems in the following cases: (1) all the particle lifetimes have finite mean, or (2) there is a type whose lifetime distribution has heavy tail, and the other lifetimes have finite mean. We get a more complex dynamics by assuming in case (2) that the most mobile particle type corresponds to a finite-mean lifetime: in this case, local extinction of the population is determined by an interaction of the parameters (offspring variability, mobility, longevity) of the long-living type and those of the most mobile type. The proofs are based on a precise analysis of the occupation times of a related Markov renewal process, which is of independent interest.

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