Abstract
We prove that for every flat surface omega, the Hausdorff dimension of the set of directions in which Teichmtiller geodesics starting from omega exhibit a definite amount of deviation from the correct limit in Birkhoff's and Oseledets' theorems is strictly less than 1. This theorem extends a result by Chaika and Eskin who proved that such sets have measure 0. We also prove that the Hausdorff dimension of the directions in which Teichmtiller geodesics diverge on average in a stratum is bounded above by 1/2, strengthening a classical result due to Masur. Moreover, we show that the Hausdorff codimension of the set of non-weakly-mixing IETs with permutation (d, d - 1, . . . , 1), where d >= 5 is an odd number, is at least 1/2, thus strengthening a result by Avila and Leguil. Combined with a recent result of Chaika and Masur, this shows that the Hausdorff dimension of this set is exactly 1/2.