Dynamical Cubes And A Criteria For Systems Having Product Extensions

Abstract

ABSTRACT. For minimal Z 2 -topological dynamical systems, we introduce a cube structure and a variation of the usual regional proximality relation for Z 2 actions, which allow us to characterize product systems and their factors. We also introduce the concept of topological magic systems, which is the topological counterpart of measure theoretic magic systems introduced by Host in his study of multiple averages for commuting transformations. Roughly speaking, magic systems have less intricate dynamics, and we show that every minimal Z 2 dynamical system has a magic extension. We give various applications of these structures, including the construction of some special factors in topological dynamics of Z 2 actions and a computation of the automorphism group of the minimal Robinson tiling.