Weak BLD mappings and Hausdorff measure

Abstract

We prove that if $Φ:X\to Y$ a mapping of weak bounded length distortion from a quasiconvex and complete metric space $X$ to any metric space $Y$, then for any Lipschitz mapping $f:\mathbb{R}^k\supset E\to X$ we have that ${\mathcal H}^k(f(E))=0$ in $X$ if and only if ${\mathcal H}^k(Φ(f(E)))=0$ in $Y$. This generalizes an earlier result of Hajłasz and Malekzadeh where the target space $Y$ was a Euclidean space $Y=\mathbb{R}^N$.