An Algebraic Invariant for Substitution Tiling Systems
arXiv:math/9712264
Abstract
We consider tilings of Euclidean spaces by polygons or polyhedra, in particular, tilings made by a substitution process, such as the Penrose tilings of the plane. We define an isomorphism invariant related to a subgroup of rotations and compute it for various examples. We also extend our analysis to more general dynamical systems.
Plain TeX. 18 pages including 5 embedded postscript figures