On the weak approximation of a skew diffusion by an Euler-type scheme

TL;DR

This paper analyzes the weak approximation error of a skew diffusion process with bounded measurable drift and H"older continuous diffusion coefficient using an Euler-type scheme, providing bounds on the density difference and error order.

Contribution

It establishes Gaussian bounds for the approximation density and quantifies the weak approximation error order as h^{η/2}, advancing understanding of numerical schemes for skew diffusions.

Findings

Gaussian bounds for the approximation density

Error order of h^{η/2} for the Euler scheme

Quantitative bounds on density differences

Abstract

We study the weak approximation error of a skew diffusion with bounded measurable drift and H\"older diffusion coefficient by an Euler-type scheme, which consists of iteratively simulating skew Brownian motions with constant drift. We first establish two sided Gaussian bounds for the density of this approximation scheme. Then, a bound for the difference between the densities of the skew diffusion and its Euler approximation is obtained. Notably, the weak approximation error is shown to be of order $h^{\eta/2}$, where $h$ is the time step of the scheme, $\eta$ being the H\"older exponent of the diffusion coefficient.