Irrationality exponent, Hausdorff dimension and effectivization

We generalize the classical theorem by Jarnik and Besicovitch on the irrationality exponents of real numbers and Hausdorff dimension and show that the two notions are independent. For any real number a greater than or equal to 2 and any non-negative real b be less than or equal to 2 / a, we show tha...

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Bibliographic Details
Authors: Becher, Veronica Andrea, Reimann, Jan, Slaman, Theodore A.
Format: article
Status:Published version
Publication Date:2018
Country:Argentina
Institution:Consejo Nacional de Investigaciones Científicas y Técnicas
Repository:CONICET Digital (CONICET)
Language:English
OAI Identifier:oai:ri.conicet.gov.ar:11336/97123
Online Access:http://hdl.handle.net/11336/97123
Access Level:Open access
Keyword:CANTOR SETS
DIOPHANTINE APPROXIMATION
EFFECTIVE HAUSDORFF DIMENSION
https://purl.org/becyt/ford/1.2
https://purl.org/becyt/ford/1
Description
Summary:We generalize the classical theorem by Jarnik and Besicovitch on the irrationality exponents of real numbers and Hausdorff dimension and show that the two notions are independent. For any real number a greater than or equal to 2 and any non-negative real b be less than or equal to 2 / a, we show that there is a Cantor-like set with Hausdorff dimension equal to b such that, with respect to its uniform measure, almost all real numbers have irrationality exponent equal to a. We give an analogous result relating the irrationality exponent and the effective Hausdorff dimension of individual real numbers. We prove that there is a Cantor-like set such that, with respect to its uniform measure, almost all elements in the set have effective Hausdorff dimension equal to b and irrationality exponent equal to a. In each case, we obtain the desired set as a distinguished path in a tree of Cantor sets.