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Schmidt’s game, fractals, and orbits of toral endomorphisms

Published online by Cambridge University Press:  05 August 2010

RYAN BRODERICK
Affiliation:
Department of Mathematics, Brandeis University, Waltham, MA 02454-9110, USA (email: [email protected], [email protected], [email protected])
LIOR FISHMAN
Affiliation:
Department of Mathematics, Brandeis University, Waltham, MA 02454-9110, USA (email: [email protected], [email protected], [email protected])
DMITRY KLEINBOCK
Affiliation:
Department of Mathematics, Brandeis University, Waltham, MA 02454-9110, USA (email: [email protected], [email protected], [email protected])

Abstract

Given an integer matrix M∈GLn(ℝ) and a point y∈ℝn/ℤn, consider the set S. G. Dani showed in 1988 that whenever M is semisimple and y∈ℚn/ℤn, the set has full Hausdorff dimension. In this paper we strengthen this result, extending it to arbitrary M∈GLn(ℝ)∩Mn×n(ℤ) and y∈ℝn/ℤn, and in fact replacing the sequence of powers of M by any lacunary sequence of (not necessarily integer) m×n matrices. Furthermore, we show that sets of the form and their generalizations always intersect with ‘sufficiently regular’ fractal subsets of ℝn. As an application, we give an alternative proof of a recent result [M. Einsiedler and J. Tseng. Badly approximable systems of affine forms, fractals, and Schmidt games. Preprint, arXiv:0912.2445] on badly approximable systems of affine forms.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2010

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