3.I.3G

Geometry of Group Actions
Part II, 2008

Let dimH\operatorname{dim}_{H} denote the Hausdorff dimension of a set in Rn\mathbb{R}^{n}. Prove that if dimH(F)<1\operatorname{dim}_{H}(F)<1 then FF is totally disconnected.

[You may assume that if f:RnRmf: \mathbb{R}^{n} \rightarrow \mathbb{R}^{m} is a Lipschitz map then

dimH(f(F))dimH(F).]\left.\operatorname{dim}_{H}(f(F)) \leqslant \operatorname{dim}_{H}(F) .\right]