English

(Uniform) Convergence of Twisted Ergodic Averages

Dynamical Systems 2019-02-20 v3 Classical Analysis and ODEs Number Theory

Abstract

Let TT be an ergodic measure-preserving transformation on a non-atomic probability space (X,Σ,μ)(X,\Sigma,\mu). We prove uniform extensions of the Wiener-Wintner theorem in two settings: For averages involving weights coming from Hardy field functions, pp: {1NnNe(p(n))Tnf(x)} \{\frac{1}{N} \sum_{n\leq N} e(p(n)) T^{n}f(x) \} and for "twisted" polynomial ergodic averages: {1NnNe(nθ)TP(n)f(x)} \{\frac{1}{N} \sum_{n\leq N} e(n \theta) T^{P(n)}f(x) \} for certain classes of badly approximable θ[0,1]\theta \in [0,1]. We also give an elementary proof that the above twisted polynomial averages converge pointwise μ\mu-a.e. for fLp(X), p>1,f \in L^p(X), \ p >1, and arbitrary θ[0,1]\theta \in [0,1].

Keywords

Cite

@article{arxiv.1407.4736,
  title  = {(Uniform) Convergence of Twisted Ergodic Averages},
  author = {Tanja Eisner and Ben Krause},
  journal= {arXiv preprint arXiv:1407.4736},
  year   = {2019}
}

Comments

31 pages, the referee's suggestions incorporated, references added, typos corrected. A uniform estimate of the ergodic averages with Hardy field weights by the corresponding Gowers-Host-Kra uniformity seminorms is added, see Theorem 2.11. To appear in Ergodic Theory Dynam. Systems