Alphabeta Math

Hausdorff Measure and Hausdorff Dimension

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1 · Prerequisites
2 · Logical flowchart

3 · Items

Definition

Extended diameter for Hausdorff covers

Definition

Hausdorff content at a prescribed scale

Lemma

The small-scale Hausdorff limit exists

Definition

Unnormalised Hausdorff measure

Theorem

Hausdorff measure is an outer measure

Theorem

Hausdorff measure is metric and measures every Borel set

Proposition

Zero-dimensional Hausdorff measure is counting measure

Theorem

Hausdorff measure is Borel regular

Proposition

Borel cores of sigma-finite Hausdorff measurable sets

Proposition

Content and measure have the same null sets

Theorem

Lipschitz maps control Hausdorff measure

Corollary

Similarities scale Hausdorff measure exactly

Lemma

Increasing the exponent past finite measure gives zero

Definition

Hausdorff dimension

Theorem

Hausdorff dimension is the unique critical exponent

Theorem

Hausdorff dimension is monotone and countably stable

Corollary

Lipschitz monotonicity and bi-Lipschitz invariance of dimension

Lemma

Elementary lower and upper bounds on a unit cube

Theorem

One-dimensional Hausdorff measure on the line is Lebesgue outer measure

Theorem

Euclidean Hausdorff measure is proportional to Lebesgue measure

Corollary

Euclidean space and positive-volume sets have their Euclidean dimension

Theorem

The mass distribution principle

Lemma

Cantor basic intervals have their expected masses

Lemma

The sharp interval bound for Cantor measure

Theorem

The Cantor set has dimension log 2 / log 3 and critical measure one

Definition

Sets defined by permitted binary digit positions

Proposition

Digit-position density determines Hausdorff dimension

Remark

Dimension leaves the critical measure undetermined

Remark

Chart surface measure and Hausdorff measure: a boundary of scope

Remark

Orientation for the published Weierstrass graph remark

Sources