Pervasiveness of the $p$-Laplace operator under localization of fractional $g$-Laplace operators

Abstract

In this work we analyze the behavior of truncated functionals as \begin{equation*} \int_{\mathbb{R}^N}\int_{B(x,\delta)} G\left(\frac{|u(x)-u(y)|}{|x-y|^{s}}\right)\frac{dydx}{|x-y|^N}\qquad\text{for }\delta\to0^+. \end{equation*} Here the function $G$ is an Orlicz function that in addition is assumed to be a regularly varying function at $0$. A prototype of such function is given by $G(t)=t^p(1+|\log(t)|)$ with $p\geq2$. These kind of functionals arise naturally in {\it peridynamics}, where long-range interactions are neglected and only those exerted at distance smaller than $\delta>0$ are taken into account, i.e., the {\it horizon} $\delta>0$ represents the range of interactions or nonlocality.\\ This work is inspired by the celebrated result by Bourgain, Brezis and Mironescu, who analyzed the limit $s\to1^-$ with $G(t)=t^p$. In particular, we prove that, under appropriate conditions, \begin{equation*} \lim\limits_{\delta\to0^+}\frac{p(1-s)}{G(\delta^{1-s})}\int_{\mathbb{R}^N}\int_{B(x,\delta)}G\left(\frac{|u(x)-u(y)|}{|x-y|^{s}}\right)\frac{dydx}{|x-y|^N}=K_{N,p}\int_{\mathbb{R}^N}|\nabla u(x)|^p dx, \end{equation*} for $p=index(G)$ and an explicit constant $K_{N,p}>0$. Moreover, the converse is also true, if the above localization limit exist as $\delta\to0^+$, the Orlicz function $G$ is a regularly varying function with $index(G)=p$.