Exact Regularity and the Cohomology of Tiling Spaces

Lorenzo Sadun

Published 2010-04-13, updated 2018-07-06Version 2

The Exact Regularity Property was introduced recently as a property of homological Pisot substitutions in one dimension. In this paper, we consider exact regularity for arbitrary tiling spaces. Let ${T}$ be a $d$ dimensional repetitive tiling, and let $\Omega_{{T}}$ be its hull. If $\check H^d(\Omega_{{T}}, Q) = Q^k$, then there exist $k$ patches whose appearance govern the number of appearances of every other patch. This gives uniform estimates on the convergence of all patch frequencies to the ergodic limit. If the tiling ${T}$ comes from a substitution, then we can quantify that convergence rate. If ${T}$ is also one-dimensional, we put constraints on the measure of any cylinder set in $\Omega_{{T}}$.