Multifunction Estimation in a Time-Discretized Skorokhod Reflection Problem
Nicolas Marie
TL;DR
The paper addresses estimating an unknown time-varying convex body $C(t)$ that governs a time-discretized Skorokhod reflection of a diffusion, using a Moreau sweeping framework. It introduces a discrete approximation $\\overline{X}_{j+1}$ and defines a convex-hull estimator $\\widehat{C}_{N,j}$ from $N$ independent copies, enabling set-valued inference for diffusion-constraint dynamics. The authors prove $1$-D consistency with rate $N$ (and $N d_{\rm H}(\\widehat{C}_{N,j}, C(t_j)) \to 0$ when $\\sigma$ is constant$)$ and establish pointwise consistency in higher dimensions under a monotonicity assumption on $C$. This advances copy-based statistical inference for reflected diffusions by providing a concrete, consistent estimator for the evolving constraint set. The results have potential applications in fields like ethology where the target’s territory evolves over time and is not directly observed.
Abstract
This paper deals with a consistent estimator of the multifunction involved in a time-discretized Skorokhod reflection problem defined by a stochastic differential equation and a Moreau sweeping process.
