2015/01/09 by Zhen-Qing Chen, Chen, Zhen-Qing, Yan-Xia Ren +3
Computer Science · Mathematics · #Advanced Mathematical Modeling in Engineering #Geometric Analysis and Curvature Flows #Nonlinear Partial Differential Equations #math.PR
paper · pdf · doi:10.48550/arxiv.1501.02023
arxiv created 2016/03/24 · arxiv updated 2016/03/25
Suppose d≥ 2 and 0<β<α<2. We consider the non-local operator Lb=Δα/2+Sb, where Sbf(x):=limε→ 0A(d,-β)∫|z|>ε(f(x+z)-f(x))\fracb(x,z)|z|d+β dy. Here b(x,z) is a bounded measurable function on ℝd×ℝd that is symmetric in z, and A(d,-β) is a normalizing constant so that when b(x, z)≡ 1, Sb becomes the fractional Laplacian Δβ/2:=-(-Δ)β/2. In other words, Lbf(x):=limε→ 0A(d,-β)∫|z|>ε(f(x+z)-f(x)) jb(x, z) dz, where jb(x, z):= A(d,-α) |z|-(d+α)+ A(d,-β) b(x, z)|z|-(d+β). It is recently established in Chen and Wang [arXiv:1312.7594 [math.PR]] that, when jb(x, z)≥ 0 on ℝd× ℝd, there is a conservative Feller process Xb having Lb as its infinitesimal generator. In this paper we establish, under certain conditions on b, a uniform boundary Harnack principle for harmonic functions of Xb (or equivalently, of Lb) in any κ-fat open set. We further establish uniform gradient estimates for non-negative harmonic functions of Xb in open sets.