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arXiv 2202.10258math.PR
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条件化为极大的布朗连续随机树

Brownian continuum random tree conditioned to be large

CNRS(法国国家科学研究中心);Beijing Normal University(北京师范大学)

Romain Abraham, Jean-Franç Ois Delmas, Hui He

AI总结:

本文研究条件化于极大值的 Feller 扩散及其谱系树极限,发现在特定增长条件下得到由 Girsanov 变换描述的新过程,其谱系树为装饰有布朗连续随机树的无限离散骨架。

摘要:

我们考虑一个 Feller 扩散(Feller diffusion,$Z_s, s \ge 0$)(具有扩散系数 $\sqrt{2\beta}$ 和漂移 $\theta \in \mathbb{R}$),将其条件化于 $\{Z_t = a_t\}$,其中 $a_t$ 是确定性函数,并研究当 $t \to +\infty$ 时条件化过程及其谱系树在分布上的极限。当 $a_t$ 增长不过快时,我们得到标准的大小偏置过程(及其由 Kesten 树给出的关联谱系树)。当 $\theta = 0$ 时 $a_t$ 表现为 $\alpha\beta^2 t^2$,或当 $\theta \neq 0$ 时表现为 $\alpha e^{2\beta|\theta|t}$,我们得到一个新过程,其分布由 Girsanov 变换描述,等价地由带有泊松移民的 SDE 描述。其关联谱系树由一个无限离散骨架(不满足分支性质)描述,该骨架装饰有由泊松点测度给出的布朗连续随机树。作为副产物,我们引入了几个赋予 Gromov 型距离的树集合,具有独立价值,并在此允许以形式化且可测的方式定义骨架与一族连续随机树的装饰。

英文摘要:

We consider a Feller diffusion (Zs, s $\ge$ 0) (with diffusion coefficient $\sqrt$ 2$β$ and drift $θ$ $\in$ R) that we condition on {Zt = at}, where at is a deterministic function, and we study the limit in distribution of the conditioned process and of its genealogical tree as t $\rightarrow$ +$\infty$. When at does not increase too rapidly, we recover the standard size-biased process (and the associated genealogical tree given by the Kesten's tree). When at behaves as $α$$β$ 2 t 2 when $θ$ = 0 or as $α$ e 2$β$|$θ$|t when $θ$ = 0, we obtain a new process whose distribution is described by a Girsanov transformation and equivalently by a SDE with a Poissonian immigration. Its associated genealogical tree is described by an infinite discrete skeleton (which does not satisfy the branching property) decorated with Brownian continuum random trees given by a Poisson point measure. As a by-product of this study, we introduce several sets of trees endowed with a Gromovtype distance which are of independent interest and which allow here to define in a formal and measurable way the decoration of a backbone with a family of continuum random trees.

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。

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