"Ellis semigroup for constant length substitutions"
Kellendonk, JohannesThe Ellis semigroup (or enveloping semigroup) of a topological dynamical system is a compactification of the group action in the topology of pointwise convergence. Its algebraic and topological properties characterise the dynamical system. It hence characterises tilings via their dynamical systems. We give an overview on recent results obtained in the analysis of this semigroup for constant length substitutions.