  We show that the viscous resistive magneto-hydrodynamics system with Hall
effect is locally well-posed in $H^s(\mathbb R^n)\times
H^{s+1-\varepsilon}(\mathbb R^n)$ with $s>\frac{n}2-1$ and any small enough
$\varepsilon>0$ such that $s+1-\varepsilon>\frac{n}2$. This space is to date
the largest local well-posedness space in the class of Sobolev spaces for the
system. It is also optimal according to the predominant scalings of the two
equations in the system.
