arXiv subjects

Jiang-Lun Wu

Publications and source records attributed to Jiang-Lun Wu.

28 records · Page 2Linked to original sources

arXiv2017

Matrix-valued SDEs arising from currency exchange markets

In this paper, motivated by modelling currency exchange markets with matrix-valued stochastic processes, matrix-valued stochastic differential equations (SDEs) are formulated. This is done based on the matrix trace, as for the purpose of modelling currency exchange markets. To be more precise, we set up a Hilbert space structure for $n\times n$ square matrices via the trace of the Hadamard product of two matrices. With the help of this framework, one can then define stochastic integral of Itô type and Itô SDEs. Two types of sufficient conditions are discussed for the existence and uniqueness of solutions to the matrix-valued SDEs.

math.PR↗

arXiv2017

Foreign exchange market modelling and an on-line portfolio selection algorithm

In this paper, we introduce a matrix-valued time series model for foreign exchange market. We then formulate trading matrices, foreign exchange options and return options (matrices), as well as on-line portfolio strategies. Moreover, we attempt to predict returns of portfolios by developing a cross rate method. This leads us to construct an on-line portfolio selection algorithm for this model. At the end, we prove the profitability and the universality of our algorithm.

q-fin.PM↗

arXiv2017

BMO estimates for stochastic singular integral operators and its application to PDEs with Lévy noise

In this paper, we consider the stochastic singular integral operators and obtain the BMO estimates. As an application, we consider the fractional Laplacian equation with additive noises \bess du_t(x)=Δ^{\fracα{2}}u_t(x)dt+\sum_{k=1}^\infty\int_{\mathbb{R}^m}g^k(t,x)z\tilde N_k(dz,dt),\ \ \ u_0=0,\ 0\leq t\leq T, \eess where $Δ^{\fracα{2}}=-(-Δ)^{\fracα{2}}$, and $\int_{\mathbb{R}^m}z\tilde N_k(t,dz)=:Y_t^k$ are independent $m$-dimensional pure jump Lévy processes with Lévy measure of $ν^k$. Following the idea of \cite{Kim}, we obtain the $q$-th order BMO quasi-norm of the $\fracα{q_0}$-order derivative of $u$ is controlled by the norm of $g$.

math.PR↗

arXiv2017

Morrey-Campanato estimates for the moments of stochastic integral operators and its application to SPDEs

In this paper, we are concerned with the estimates for the moments of stochastic convolution integrals. We first deal with the stochastic singular integral operators and we aim to derive the Morrey-Campanato estimates for the $p$-moments (for $p\ge1$). Then, by utilising the embedding theory between the Campanato space and Hölder space, we establish the norm of $C^{θ,θ/2}(\bar D)$, where $θ\ge0, \bar D=\bar G\times[0,T]$ for arbitrarily fixed $T\in(0,\infty)$ and $G\subset\mathbb{R}^d$. As an application, we consider the following stochastic (fractional) heat equations with additive noises \bess du_t(x)=Δ^αu_t(x)dt+g(t,x)dη_t,\ \ \ u_0=0,\ 0\leq t\leq T, x\in G, \eess where $Δ^α=-(-Δ)^α$ with $0<α\leq1$ (the fractional Laplacian), $g:[0,T]\times G\timesΩ\to\mathbb{R}$ is a joint measurable coefficient, and $η_t, t\in[0,T]$, is either the Brownian motion or a Lévy process on a given filtered probability space $(Ω,\mathcal{F},P;\{\mathcal{F}_t\}_{t\in[0,T]})$. The Schauder estimate for the $p$-moments of the solution of the above equation is obtained. The novelty of the present paper is that we obtain the Schauder estimate for parabolic stochastic partial differential equations with Lévy noise.

math.PR↗

arXiv2016

Characterizing the path-independent property of the Girsanov density for degenerated stochastic differential equations

In this paper, we derive a characterization theorem for the path-independent property of the density of the Girsanov transformation for {\it degenerated} stochastic differential equations (SDEs), extending the characterization theorem of \cite{twwy} for the non-degenerated SDEs. We further extends our consideration to non-Lipschitz SDEs with jumps and with degenerated diffusion coefficients, which generalizes the corresponding characterization theorem established in \cite{hqwu}.

math.PR↗

arXiv2014

Stochastic continuity, irreducibility and non confluence for SDEs with jumps

In this paper, we investigate stochastic continuity (with respect to the initial value), irreducibility and non confluence property of the solutions of stochastic differential equations with jumps. The conditions we posed are weaker than those relevant conditions existing in the literature. We also provide an example to support our new conditions.

math.PR↗

arXiv2014

Existence and uniqueness of global strong solutions for SDEs with jumps under a new sufficient condition

In this paper, we investigate new sufficient conditions to ensure the existence of a unique global strong solution of stochastic differential equations with jumps. By using Euler approximation and by utilising a new test function $φ_δ$ (see the following definition (\ref{pntas1})), we prove that there is a unique global strong solution for the initial value problem of the equation. The condition we posed is even weaker than the local Lipschitzian continuity of the coefficients. We also present an example to show that our conditions are indeed weaker than those relevant conditions existing in the literature.

math.PR↗

arXiv2014

New sufficient conditions of existence, moment estimations and non confluence for SDEs with non-Lipschitzian coefficients

The object of the present paper is to find new sufficient conditions for the existence of unique strong solutions to a class of (time-inhomogeneous) stochastic differential equations with random, non-Lipschitzian coefficients. We give an example to show that our conditions are indeed weaker than those relevant conditions existing in the literature. We also derive moment estimations for the maximum process of the solution. Finally, we present a sufficient condition to ensure the non confluence property of the solution of time-homogeneous SDE which, in one dimension, is nothing but stochastic monotone property of the solution.

math.PR↗

arXiv2013

A Galerkin approximation scheme for the mean correction in a mean-reversion stochastic differential equation

This paper is concerned with the following Markovian stochastic differential equation of mean-reversion type \[ dR_t= (θ+σα(R_t, t))R_t dt +σR_t dB_t \] with an initial value $R_0=r_0\in\mathbb{R}$, where $θ\in\mathbb{R}$ and $σ>0$ are constants, and the mean correction function $α:\mathbb{R}\times[0,\infty)\to α(x,t)\in\mathbb{R}$ is twice continuously differentiable in $x$ and continuously differentiable in $t$. We first derive that under the assumption of path independence of the density process of Girsanov transformation for the above stochastic differential equation, the mean correction function $α$ satisfies a non-linear partial differential equation which is known as the viscous Burgers equation. We then develop a Galerkin type approximation scheme for the function $α$ by utilizing truncation of discretised Fourier transformation to the viscous Burgers equation.

q-fin.PR↗

arXiv2010

Log-Harnack Inequality for Stochastic Burgers Equations and Applications

By proving an $L^2$-gradient estimate for the corresponding Galerkin approximations, the log-Harnack inequality is established for the semigroup associated to a class of stochastic Burgers equations. As applications, we derive the strong Feller property of the semigroup, the irreducibility of the solution, the entropy-cost inequality for the adjoint semigroup, and entropy upper bounds of the transition density.

math.PR↗