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arXiv 0909.1823math.PR
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Wiener泛函的弱逼近

Weak approximations for Wiener functionals

Dorival Leão, Alberto Ohashi

摘要:

在本文中,我们介绍了一个简单的空间过滤离散计划的Wiener空间,使我们能够研究弱分解和光滑显式逼近的一大类Wiener泛函。我们证明了任何Wiener泛函都有一个鲁棒半鞅骨架,在温和的条件下,该骨架收敛于它。离散化是根据离散跳跃滤波给出的,这使得我们可以通过Wiener空间上的随机导数算子来逼近非光滑过程。作为副产品,我们提供了一个强大的半鞅逼近弱Dirichlet型过程。潜在的半鞅骨架本质上是以这样的方式构造的,即所有相关的结构都服从于一个鲁棒的数值方案。为了说明结果,我们提供了一个易于实现的近似计划的经典Clark-Ocone公式在充分的一般性。与以前的作品不同,我们的方法不假设一个潜在的马尔可夫结构,不需要Malliavin权重。最后,我们提出了一种方法,使我们能够计算可能的非马尔可夫系统所产生的最佳停时,例如,从分数布朗运动。

英文摘要:

In this paper we introduce a simple space-filtration discretization scheme on Wiener space which allows us to study weak decompositions and smooth explicit approximations for a large class of Wiener functionals. We show that any Wiener functional has an underlying robust semimartingale skeleton which under mild conditions converges to it. The discretization is given in terms of discrete-jumping filtrations which allow us to approximate nonsmooth processes by means of a stochastic derivative operator on the Wiener space. As a by-product, we provide a robust semimartingale approximation for weak Dirichlet-type processes. The underlying semimartingale skeleton is intrinsically constructed in such way that all the relevant structure is amenable to a robust numerical scheme. In order to illustrate the results, we provide an easily implementable approximation scheme for the classical Clark-Ocone formula in full generality. Unlike in previous works, our methodology does not assume an underlying Markovian structure and does not require Malliavin weights. We conclude by proposing a method that enables us to compute optimal stopping times for possibly non-Markovian systems arising, for example, from the fractional Brownian motion.

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