Ergodic pairs for fractional Hamilton-Jacobi equations on bounded domains: large solutions
Alexander Quaas, Erwin Topp
TL;DR
This work establishes the existence and qualitative structure of ergodic pairs for a fractional Hamilton–Jacobi equation on a bounded domain with censored diffusion. Using the vanishing discount method applied to the discounted problem $\lambda u + (-\Delta)_\Omega^s u + |Du|^m = f$, the authors obtain a minimal large solution and derive precise blow-up rates near the boundary via the distance function through $g_\gamma$. They prove the existence of an ergodic pair $(u,c)$ with $(-\Delta)_\Omega^s u + |Du|^m = f - c$ in $\Omega$ and $u(x)\to\infty$ as $x\to\partial\Omega$, with $u\in C^{2s+\alpha}(\Omega)$ and $u$ in the $\gamma$-class, and they characterize the ergodic constant $c$ as a critical value. The results reveal partial uniqueness in the $\gamma$-class and minimality up to additive constants, while addressing the nonlocal state-dependent operator and boundary blow-up. The findings contribute to understanding large-time behavior and stochastic control with state constraints in nonlocal diffusion settings, and they lay groundwork for further uniqueness and Liouville-type results for censored operators.
Abstract
In this article, we study the ergodic problem associated to viscous Hamilton-Jacobi equation where the diffusion is governed by the censored fractional Laplacian, a nonlocal elliptic operator restricted to a bounded domain $Ω\subset \mathbb{R}^N$. We restrict ourselves to the case in which the nonlinear gradient term has a scaling less or equal than the fractional order of the diffusion. In similarity to its second-order counterpart, we provide existence of ergodic pairs involving solutions that blow-up on $\partial Ω$. We use the celebrated vanishing discount method, where the analysis of the approximated solutions have its own interest, leading to qualitative properties for the ergodic problem such as precise blow-up rates for the solution and characterization of the ergodic constant. The main difficulties arise from the state-dependency of the operator, from which the arguments of the local case based on well-known invariance properties of the Laplacian are not longer at disposal.
