Abstract:
The talk is based on works of J.P.Bell, D.Ghioca, and T.J.Tucker.
Let $x \in X$ be a point in a Noetherian space,
let $f:X \rightarrow X$ be a continuous function, and let $Y \subset X$ be a
closed set.
We show that the set $S := {n \in \mathbb{N}: f^n(x) \in Y}$ is a union of
finitely many arithmetic progressions and
a set with Banach density zero. We also discuss some corollaries of this
result.