Return time sets and product recurrence

Abstract

Let $G$ be a countable infinite discrete group. We show that a subset $F$ of $G$ contains a return time set of some piecewise syndetic recurrent point $x$ in a compact Hausdorff space $X$ with a $G$-action if and only if $F$ is a quasi-central set. As an application, we show that if a nonempty closed subsemigroup $S$ of the Stone-Čech compactification ${\hat{I}}^{2}G$ contains the smallest ideal $K({\hat{I}}^{2}G)$ of ${\hat{I}}^{2}G$ then $S$-product recurrent is equivalent to distality, which partially answers a question of Auslander and Furstenberg (Trans. Amer. Math. Soc. 343, 1994, 221--232).

32 pages, to appear in Fund. Math