Intersection Local Times of Independent Fractional Brownian Motions as Generalized White Noise Functionals

In this work we present expansions of intersection local times of fractional Brownian motions in ? ^d , for any dimension d??1, with arbitrary Hurst coefficients in (0,1) ^d . The expansions are in terms of Wick powers of white noises (corresponding to multiple Wiener integrals), being well-defined in the sense of generalized white noise functionals. As an application of our approach, a sufficient condition on d for the existence of intersection local times in L ² is derived, extending the results in Nualart and Ortiz-Latorre (J. Theoret. Probab. 20(4):759?C767, 2007) to different and more general Hurst coefficients.     

Intersection Local Time for Two Independent Fractional Brownian Motions

Let B ^H and be two independent, d-dimensional fractional Brownian motions with Hurst parameter H∈(0,1). Assume d≥2. We prove that the intersection local time of B ^H and

Intersection Local Times of Independent Brownian Motions as Generalized White Noise Functionals

A 'chaos expansion' of the intersection local time functional of two independent Brownian motions in R ^d is given. The expansion is in terms of normal products of white noise (corresponding to multiple Wiener integrals). As a consequence of the local structure of the normal products, the kernel functions in the expansion are explicitly given and exhibit clearly the dimension dependent singularities of the local time functional. Their L ^p -properties are discussed. An important tool for deriving the chaos expansion is a computation of the 'S-transform' of the corresponding regularized intersection local times and a control about their singular limit.     

On the Collision Local Time of Fractional Brownian Motions

In this paper, the existence and smoothness of the collision local time are proved for two independent fractional Brownian motions, through L2 convergence and Chaos expansion. Furthermore, the regularity of the collision local time process is studied.     

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Let, be two independent,
-dimensional sub-fractional Brownian motions with respective indices.
Assume. Our principal results are the necessary and sufficient condition for the
existence and smoothness of the collision local time and the intersection local time of
and through chaos expansion and elementary inequalities.     

Differentiability of Fractional Integrals Whose Kernels Contain Fractional Brownian Motions

We prove the stochastic Fubini theorem for Wiener integrals with respect to fractional Brownian motions. By using this theorem, we establish conditions for the mean-square and pathwise differentiability of fractional integrals whose kernels contain fractional Brownian motions.     

Convergence in Law to Operator Fractional Brownian Motions

In this paper, we provide two approximations in law of operator fractional Brownian motions. One is constructed by Poisson processes, and the other generalizes a result of Taqqu (Z. Wahrscheinlichkeitstheor. Verw. Geb. 31:287–302, 1975).     

Regularity of the Local Time for the d-dimensional Fractional Brownian Motion with N-parameters

ABSTRACT

We give the Wiener–Ito? chaotic decomposition for the local time of the d-dimensional fractional Brownian motion with N-parameters and study its smoothness in the Sobolev–Watanabe spaces.     

Simulation of First-Passage Times for Alternating Brownian Motions

The first-passage-time problem for a Brownian motion with alternating infinitesimal moments through a constant boundary is considered under the assumption that the time intervals between consecutive changes of these moments are described by an alternating renewal process. Bounds to the first-passage-time density and distribution function are obtained, and a simulation procedure to estimate first-passage-time densities is constructed. Examples of applications to problems in environmental sciences and mathematical finance are also provided.AMS 2000 Subject Classification: 60J65, 60G40, 93E30     

Singularity of Fractional Brownian Motions with Different Hurst Indices

Abstract

We prove that the probability measures generated by two fractional Brownian motions with different Hurst indices are singular with respect to each other.     

Limit Theorems for Logarithmic Averages of Fractional Brownian Motions

We prove almost sure invariance principles for logarithmic averages of fractional Brownian motions.Research supported byResearch supported by     

Reaction-Diffusion Equations with Polynomial Drifts Driven by Fractional Brownian Motions

A reaction-diffusion equation on [0, 1] ^d with the heat conductivity κ > 0, a polynomial drift term and an additive noise, fractional in time with H > 1/2, and colored in space, is considered. We have shown the existence, uniqueness and uniform boundedness of solution with respect to κ. Also we show that if κ tends to infinity, then the corresponding solutions of the equation converge to a process satisfying a stochastic ordinary differential equation.     

Small Ball Constants and Tight Eigenvalue Asymptotics for Fractional Brownian Motions

In this paper we prove rigorous large n asymptotics for the Karhunen–Loeve eigenvalues of a fractional Brownian motion. From the asymptotics of the eigenvalues the exact constants for small L ₂ ball estimates for fractional Brownian motions follows in a straightforward way.     

Maximum Principle for General Controlled Systems Driven by Fractional Brownian Motions

We obtain a maximum principle for stochastic control problem of general controlled stochastic differential systems driven by fractional Brownian motions (of Hurst parameter H>1/2). This maximum principle specifies a system of equations that the optimal control must satisfy (necessary condition for the optimal control). This system of equations consists of a backward stochastic differential equation driven by both fractional Brownian motions and the corresponding underlying standard Brownian motions. In addition to this backward equation, the maximum principle also involves the Malliavin derivatives. Our approach is to use conditioning and Malliavin calculus. To arrive at our maximum principle we need to develop some new results of stochastic analysis of the controlled systems driven by fractional Brownian motions via fractional calculus. Our approach of conditioning and Malliavin calculus is also applied to classical system driven by standard Brownian motions while the controller has only partial information. As a straightforward consequence, the classical maximum principle is also deduced in this more natural and simpler way.     

分数布朗运动下带违约风险的可转换债券定价模型

在股票价格、公司资产价值均服从分数次布朗运动且相关的条件下,利用风险对冲方法导出带违约风险的可转换债券定价模型;然后,通过解相关的偏微分方程得到其显式定价公式.     

Integration by Parts Formula and Applications for SDEs Driven by Fractional Brownian Motions

By using coupling by change of measures, the Driver-type integration by parts formula is established for a class of stochastic differential equations driven by fractional Brownian motions. As applications, (log) shift Harnack inequalities and estimates on the distribution density of the solutions are presented.     

Intersection Local Times as Generalized White Noise Functionals

For any dimension we present the expansions of Brownian motion self-intersection local times in terms of multiple Wiener integrals. Suitably subtracted, they exist in the sense of generalized white noise functionals; their kernel functions are given in closed (and remarkably simple) form.     

Bouncing Skew Brownian Motions

We consider two skew Brownian motions, driven by the same Brownian motion, with different starting points and different skewness coefficients. In Gloter and Martinez (Ann Probab 41(3A):1628–1655, 2013), the evolution of the distance between the two processes, in local timescale and up to their first hitting time, is shown to satisfy a stochastic differential equation with jumps driven by the excursion process of one of the two skew Brownian motions. In this article, we show that the distance between the two processes in local timescale may be viewed as the unique continuous Markovian self-similar extension of the process described in Gloter and Martinez (2013). This permits us to compute the law of the distance of the two skew Brownian motions at any time in the local timescale, when both original skew Brownian motions start from zero. As a consequence, we give an explicit formula for the entrance law of the associated excursion process and study the Markovian dependence on the skewness parameter. The results are related to an open question formulated initially by Burdzy and Chen (Ann Probab 29(4):1693–1715, 2001).     

分式Brown运动的局部时:白噪声分析法

本文利用白噪声分析的方法,讨论了分式布朗运动的局部时,即将其看作一个Hida分布.进一步,给出分式布朗运动的局部时的混沌分解以及局部时平方可积性.