English

On $n$-tuplewise IP-sensitivity and thick sensitivity

Dynamical Systems 2022-08-26 v3

Abstract

Let (X,T)(X,T) be a topological dynamical system and n2n\geq 2. We say that (X,T)(X,T) is nn-tuplewise IP-sensitive (resp. nn-tuplewise thickly sensitive) if there exists a constant δ>0\delta>0 with the property that for each non-empty open subset UU of XX, there exist x1,x2,,xnUx_1,x_2,\dotsc,x_n\in U such that {kN ⁣:min1i<jnd(Tkxi,Tkxj)>δ} \Bigl\{k\in\mathbb{N}\colon \min_{1\le i<j\le n}d(T^k x_i,T^k x_j)>\delta\Bigr\} is an IP-set (resp. a thick set). We obtain several sufficient and necessary conditions of a dynamical system to be nn-tuplewise IP-sensitive or nn-tuplewise thickly sensitive and show that any non-trivial weakly mixing system is nn-tuplewise IP-sensitive for all n2n\geq 2, while it is nn-tuplewise thickly sensitive if and only if it has at least nn minimal points. We characterize two kinds of sensitivity by considering some kind of factor maps. We introduce the opposite side of pairwise IP-sensitivity and pairwise thick sensitivity, named (almost) pairwise IP^*-equicontinuity and (almost) pairwise syndetic equicontinuity, and obtain dichotomies results for them. In particular, we show that a minimal system is distal if and only if it is pairwise IP^*-equicontinuous. We show that every minimal system admits a maximal almost pairwise IP^*-equicontinuous factor and admits a maximal pairwise syndetic equicontinuous factor, and characterize them by the factor maps to their maximal distal factors.

Cite

@article{arxiv.2108.01271,
  title  = {On $n$-tuplewise IP-sensitivity and thick sensitivity},
  author = {Jian Li and Yini Yang},
  journal= {arXiv preprint arXiv:2108.01271},
  year   = {2022}
}

Comments

19 pages. Minor changes. To appear in Discrete and Continuous Dynamical Systems

R2 v1 2026-06-24T04:46:41.382Z