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arXiv 2410.19952math.STstat.MEstat.TH
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Lévy 图模型

Lévy graphical models

Sebastian Engelke, Jevgenijs Ivanovs, Jakob D. Thøstesen

AI总结:

针对高维 Lévy 过程缺乏条件独立性与图模型研究的问题,本文基于 Lévy-Itô 分解推导跳跃过程条件独立性刻画,定义 Lévy 图模型并证明图结构不变性,开发了树结构的图恢复统计方法,应用于股票收益建模。

摘要:

条件独立性与图模型是高维稀疏性与统计建模的关键概念。对于广泛应用的一类随机过程——Lévy 过程,这些概念尚未得到研究。根据 Lévy-Itô 分解,多元 Lévy 过程可分解为 Brownian 运动部分与独立跳跃过程之和。我们证明,边际过程间的条件独立性陈述可针对这两部分分别研究。Brownian 部分已广为人知,而我们推导出跳跃过程样本路径间条件独立性基于 Lévy 测度的新颖刻画。我们将 Lévy 图模型定义为满足无向或有向 Markov 性质的 Lévy 过程。我们证明图结构在单变量边际过程变化下保持不变。Lévy 图模型允许在高维下为 Lévy 过程构建灵活且稀疏的依赖模型,且由于底层图而具有可解释性。对于树结构,我们开发了从 Lévy 过程的低频或高频观测中学习底层结构的统计方法,并证明能一致地恢复图结构。我们将该方法应用于美国公司股票收益建模,以展示本方法的优势。

英文摘要:

Conditional independence and graphical models are crucial concepts for sparsity and statistical modeling in higher dimensions. For Lévy processes, a widely applied class of stochastic processes, these notions have not been studied. By the Lévy-Itô decomposition, a multivariate Lévy process can be decomposed into the sum of a Brownian motion part and an independent jump process. We show that conditional independence statements between the marginal processes can be studied separately for these two parts. While the Brownian part is well-understood, we derive a novel characterization of conditional independence between the sample paths of the jump process in terms of the Lévy measure. We define Lévy graphical models as Lévy processes that satisfy undirected or directed Markov properties. We prove that the graph structure is invariant under changes of the univariate marginal processes. Lévy graphical models allow the construction of flexible, sparse dependence models for Lévy processes in large dimensions, which are interpretable thanks to the underlying graph. For trees, we develop statistical methodology to learn the underlying structure from low- or high-frequency observations of the Lévy process and show consistent graph recovery. We apply our method to model stock returns from U.S. companies to illustrate the advantages of our approach.

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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