Liouville type results for the fractional truncated Laplacians in a half-space
Giulio Galise, Hitoshi Ishii
TL;DR
The paper analyzes half-space problems for fully nonlinear integral operators given by the fractional truncated Laplacians $\mathcal I_k^\pm$, focusing on the balance between diffusion along lower-dimensional directions and a power nonlinearity $u^p$. It develops Liouville-type nonexistence results for various regimes of $p$ (including singular $p<0$ and sublinear $0<p\le1$) and derives threshold exponents that separate existence from nonexistence, with refined results for special cases $k=1$ and $s$ in $[\tfrac12,1)$. In parallel, it proves existence of supersolutions in complementary regimes: nonnegative supersolutions for all $p>0$ in the minimal operators, and decaying positive supersolutions for large $p$ in the maximal case, including explicit barrier constructions $u_\gamma$ and $\psi$ that drive the analysis. The results collectively map the feasibility of positive supersolutions across operator families $\mathcal I_k^\pm$ in $\mathbb R^N_+$, contributing to the understanding of nonlocal, degenerate elliptic equations and their connections to stochastic control and Liouville-type phenomena.
Abstract
Existence issues of viscosity supersolutions in the half-space $\mathbb R^N_+$, for a class of fully nonlinear integral equations involving the fractional truncated Laplacians and a power-like nonlinearity in the unknown function, are addressed in this paper, the aim being to obtain estimates on the threshold exponents separating the existence from the nonexistence regimes.
