Potential method and projection theorems for macroscopic Hausdorff dimension

Abstract

The macroscopic Hausdorff dimension Dim H (E) of a set E $\subset$ R d was introduced by Barlow and Taylor to quantify a "fractal at large scales" behavior of unbounded, possibly discrete, sets E. We develop a method based on potential theory in order to estimate this dimension in R d. Then, we apply this method to obtain Marstrand-like projection theorems: given a set E $\subset$ R 2 , for almost every $\theta$ $\in$ [0, 2$\pi$], the projection of E on the straight line passing through 0 with angle $\theta$ has dimension equal to min(Dim H (E) , 1).