A Harnack inequality and Hölder continuity for weak solutions to parabolic operators involving Hörmander vector fields

Abstract

This paper deals with two separate but related results. First we consider weak solutions to a parabolic operator with Hörmander vector fields. Adapting the iteration scheme of Jürgen Moser for elliptic and parabolic equations in ${\mathbb{R}}^n$ we show a parabolic Harnack inequality. Then, after proving the Harnack inequality for weak solutions to equations of the form $u_t=\sum X_i(a_{ij}{X}_{j}u)$ we use this to show Hölder continuity. We assume the coefficients are bounded and elliptic. The iteration scheme is a tool that may be adapted to many settings and we extend this to nonlinear parabolic equations of the form $u_t=-X_i^{\ast }{A}_j(X_{j}u)$. With this we show both a Harnack inequality and Hölder continuity of weak solutions.

References in corpus (2)

• Minimal surfaces in the Heisenberg group
• Hypoellipticity for linear degenerate elliptic systems in Carnot groups and applications