Special Session 108: Regularity in local versus nonlocal problems

Non-Diagonal Quasilinear Degenerate Elliptic Systems: Existence and Regularity
Patrizia Di Gironimo
Dipartimento di Matematica, Università di Salerno
Italy
Co-Author(s):    
Abstract:
In this talk, we discuss non-diagonal vectorial quasilinear degenerate elliptic systems defined on a bounded open set $\Omega \subset mathbb{R}^n$, with $n > 2$, of the form \begin{equation} \label{eq_divergenza} \begin{cases} - \text{div} (a(x,u(x))Du(x))= f(x) ,& x \in \Omega \ u=0, & x \in \partial \Omega \end{cases} \end{equation} where $u, f : \Omega \to \mathbb{R}^N$ and $a: \Omega \times \mathbb{R}^N \to \mathbb{R}^{N^2 n^2}$ is a bounded Carath\`{e}odory function. Unlike the scalar case, in the vectorial setting $(N \ge 2)$ one cannot generally expect boundedness or high integrability of solutions, even for regular data. We will show how, by imposing conditions on the support of the off-diagonal coefficients, it is possible to guarantee existence of solutions whose regularity depends on the datum f. In particular, we will analyze the case where f belongs to an appropriate Marcinkiewicz space, highlighting regularity properties for the systems under consideration.