TY - JOUR

T1 - Random walks on homogeneous spaces and Diophantine approximation on fractals

AU - Simmons, David Samuel

AU - Barak, Weiss

N1 - © Springer-Verlag GmbH Germany, part of Springer Nature 2019. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2019/5/1

Y1 - 2019/5/1

N2 - We extend results of Y. Benoist and J.-F. Quint concerning random walks on homogeneous spaces of simple Lie groups to the case where the measure defining the random walk generates a semigroup which is not necessarily Zariski dense, but satisfies some expansion properties for the adjoint action. Using these dynamical results, we study Diophantine properties of typical points on some self-similar fractals in R
d. As examples, we show that for any self-similar fractal K⊆ R
d satisfying the open set condition (for instance any translate or dilate of Cantor’s middle thirds set or of a Koch snowflake), almost every point with respect to the natural measure on K is not badly approximable. Furthermore, almost every point on the fractal is of generic type, which means (in the one-dimensional case) that its continued fraction expansion contains all finite words with the frequencies predicted by the Gauss measure. We prove analogous results for matrix approximation, and for the case of fractals defined by Möbius transformations.

AB - We extend results of Y. Benoist and J.-F. Quint concerning random walks on homogeneous spaces of simple Lie groups to the case where the measure defining the random walk generates a semigroup which is not necessarily Zariski dense, but satisfies some expansion properties for the adjoint action. Using these dynamical results, we study Diophantine properties of typical points on some self-similar fractals in R
d. As examples, we show that for any self-similar fractal K⊆ R
d satisfying the open set condition (for instance any translate or dilate of Cantor’s middle thirds set or of a Koch snowflake), almost every point with respect to the natural measure on K is not badly approximable. Furthermore, almost every point on the fractal is of generic type, which means (in the one-dimensional case) that its continued fraction expansion contains all finite words with the frequencies predicted by the Gauss measure. We prove analogous results for matrix approximation, and for the case of fractals defined by Möbius transformations.

UR - http://www.scopus.com/inward/record.url?scp=85060690739&partnerID=8YFLogxK

U2 - 10.1007/s00222-019-00856-7

DO - 10.1007/s00222-019-00856-7

M3 - Article

VL - 216

SP - 337

EP - 394

JO - Inventiones Mathematicae

JF - Inventiones Mathematicae

SN - 1432-1297

IS - 2

ER -