MathDB
Iterates in [n,n+1) with given upper density

Source: Miklós Schweitzer 2016, Problem 5

November 2, 2016
real analysisalgebraDensityMiklos Schweitzercombinatorics

Problem Statement

Does there exist a piecewise linear continuous function f:RRf:\mathbb{R}\to \mathbb{R} such that for any two-way infinite sequence an[0,1]a_n\in[0,1], nZn\in\mathbb{Z}, there exists an xRx\in\mathbb{R} with lim supK#{kK:kN,fk(x)[n,n+1)}K=an \limsup_{K\to \infty} \frac{\#\{k\le K\,:\, k\in\mathbb{N},f^k(x)\in[n,n+1)\}}{K}=a_n for all nZn\in\mathbb{Z}, where fk=ffff^k=f\circ f\circ \dots\circ f stands for the kk-fold iterate of ff?