Eigenvalues for systems of fractional $p-$Laplacians

Abstract

We study the eigenvalue problem for a system of fractional $p-$Laplacians, that is, $$ \begin{cases} (-\Delta_p)^r u = \lambda\dfrac{\alpha}p|u|^{\alpha-2}u|v|^{\beta} &\text{in } \Omega,\vspace{.1cm} (-\Delta_p)^s u = \lambda\dfrac{\beta}p|u|^{\alpha}|v|^{\beta-2}v &\text{in } \Omega, u=v=0 &\text{in }\Omega^c=\R^N\setminus\Omega. \end{cases} $$ We show that there is a first (smallest) eigenvalue that is simple and has associated eigen-pairs composed of positive and bounded functions. Moreover, there is a sequence of eigenvalues $\lambda_n$ such that $\lambda_n\to\infty$ as $n\to\infty$. In addition, we study the limit as $p\to \infty$ of the first eigenvalue, $\lambda_{1,p}$, and we obtain $ [\lambda_{1,p}]^{\nicefrac{1}{p}}\to \Lambda_{1,\infty} $ as $p\to\infty,$ where $$ \Lambda_{1,\infty} = \inf_{(u,v)} \left\{ \frac{\max \{ [u]_{r,\infty} ; [v]_{s,\infty} \} }{ \| |u|^{\Gamma} |v|^{1-\Gamma} \|_{L^\infty (\Omega)} } \right\} = \left[ \frac{1}{R(\Omega)} \right]^{ (1-\Gamma) s + \Gamma r }. $$ Here $R(\Omega):=\max_{x\in\Omega}\dist(x,\partial\Omega)$ and $[w]_{t,\infty} \coloneqq \sup_{(x,y)\in\overline{\Omega}} \frac{| w(y) - w(x)|}{|x-y|^{t}}.$ Finally, we identify a PDE problem satisfied, in the viscosity sense, by any possible uniform limit along subsequences of the eigen-pairs.