Word length statistics for Teichmuller geodesics and singularity of harmonic measure

Gadre, V. , Maher, J. and Tiozzo, G. (2017) Word length statistics for Teichmuller geodesics and singularity of harmonic measure. Commentarii Mathematici Helvetici, 92(1), pp. 1-36. (doi: 10.4171/CMH/404)

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Abstract

Given a measure on the Thurston boundary of Teichmuller space, one can pick a geodesic ray joining some basepoint to a randomly chosen point on the boundary. Different choices of measures may yield typical geodesics with different geometric properties. In particular, we consider two families of measures: the ones which belong to the Lebesgue or visual measure class, and harmonic measures for random walks on the mapping class group generated by a distribution with finite first moment in the word metric. We consider the word length of approximating mapping class group elements along a geodesic ray, and prove that this quantity grows superlinearly in time along almost all geodesics with respect to Lebesgue measure, while along almost all geodesics with respect to harmonic measure the growth is linear. As a corollary, the harmonic and Lebesgue measures are mutually singular. We also prove a similar result for the ratio between the word metric and the relative metric (i.e. the induced metric on the curve complex).

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Gadre, Dr Vaibhav
Authors: Gadre, V., Maher, J., and Tiozzo, G.
Subjects:Q Science > QA Mathematics
College/School:College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Commentarii Mathematici Helvetici
Publisher:European Mathematical Society
ISSN:0010-2571
ISSN (Online):1420-8946
Published Online:24 February 2017

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