Jacobians on Lipschitz domains of $\mathbbR^2$

Abstract

In this note we prove estimates of Jacobian determinants of $Du$ on strongly Lipschitz domains $\Omega$ in $\mathbbR^2$. The theorem consists of two parts: one is an estimate in terms of the $BMO_r(\Omega)$ norm for $u$ in the Sobolev space $W^{1,2}(\Omega,\mathbbR^@)$ with boundary zero, and another is an estimate in terms of the $BMO_z(\omega)$ norm for $u$ in $W^{1,2}(\Omega,\mathbbR^2)$ with no boundary conditions.