Constant-length substitutions and countable scrambled sets
  In this paper we provide examples of topological dynamical systems having either finite or countable scrambled sets. In particular we study conditions for the existence of Li-Yorke, asymptotic and distal pairs in constant--length substitution dynamical systems. Starting from a circle rotation we also construct a dynamical system having Li--Yorke pairs, none of which is recurrent. 
Fran\c{c}ois Blanchard (IML), Fabien Durand (LAMFA), Alejandro Maass   (CMM)