## Real Analysis Exchange

### Hausdorff measures of different dimensions are isomorphic under the continuum hypothesis.

Márton Elekes

#### Abstract

We show that the Continuum Hypothesis implies that for every $0 < d_1 \leq d_2 < n$ the measure spaces $(\mathbb{R}^n,\mathcal{M}_{\mathcal{H}^{d_1}},\mathcal {H}^{d_1})$ and $(\mathbb{R}^n,\mathcal{M}_{\mathcal{H}^{d_2}},\mathcal{H}^{d_2})$ are isomorphic, where $\mathcal{H}^d$ is $d$-dimensional Hausdorff measure and $\mathcal{M}_{d}$ is the $\sigma$-algebra of measurable sets with respect to $\mathcal{H}^d$. This is motivated by the well-known question (circulated by D. Preiss) whether such an isomorphism exists if we replace measurable sets by Borel sets. We also investigate the related question whether every continuous function (or the typical continuous function) is Hölder continuous (or is of bounded variation) on a set of positive Hausdorff dimension.

#### Article information

Source
Real Anal. Exchange, Volume 30, Number 2 (2004), 605 - 616 .

Dates
First available in Project Euclid: 15 October 2005

https://projecteuclid.org/euclid.rae/1129416465

Mathematical Reviews number (MathSciNet)
MR2177422

Zentralblatt MATH identifier
1106.28002

#### Citation

Elekes, Márton. Hausdorff measures of different dimensions are isomorphic under the continuum hypothesis. Real Anal. Exchange 30 (2004), no. 2, 605 -- 616. https://projecteuclid.org/euclid.rae/1129416465

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