Special Session 80: 

H\\older regularity for bounded solutions to a class of anisotropic elliptic equations by using a parabolic approach.

Stella Maria Piro (Vernier)
University of Cagliari
Italy
Co-Author(s):    Francesco Ragnedda and Vincenzo Vespri
Abstract:
In this talk we consider bounded local weak solutions to the following class of anisotropic elliptic equations \begin{equation} \label{first eq} \sum_{i=1}^{N-1} \frac {\partial } {\partial x_i} A_{q,i}(x,u, Du) + \frac {\partial} {\partial x_N }A_p( x,u, Du) = 0 \quad \mbox{in} \ \ \Omega, \end{equation} with $\Omega$ a regular domain in $\mathbb{R}^N. $ The functions $A_{q,i}(x,u,D u)$ and $A_p(x,u,D u) : \Omega \times \mathbb{R}^{N+1} \rightarrow \mathbb{R}^N$ are assumed to be measurable and satisfying the structure conditions.\ We prove the H\older regularity of solutions to \ref{first eq} when $p>q>1$ (singular case). A first step to face this problem was made by Liskevich and Skrypnik (\cite {LS}) in 2009. Then Duzgum, Marcellini and Vespri (\cite {DMV}) in 2014 extended the result proved in \cite {LS} to the case when in the equation \ref{first eq} it is assumed $q>p>1$ (degenerate case). The results have been established in a joint research with Francesco Ragnedda (Cagliari) e Vincenzo Vespri (Firenze).\ \begin{thebibliography}{99} \bibitem{DMV} F.G. D\uzg\un, P. Marcellini and V. Vespri, Space expansion for a solution of an anisotropic $p$-Laplacian equation by using a parabolic approach, {\it Riv. Math. Univ. Parma, {\bf 5}, (2014), 93 --111}. \bibitem{LS} V. Liskevich and I.I. Skrypnik, H\older continuity of solutions to an anisotropic elliptic equation, {\it Nonlinear Anal., {\bf 71}, (2009), 1699--1708}. \end{thebibliography}